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Amorphous CoSiB/Pt multilayer is a perpendicular magnetic anisotropy material to achieve high squareness, low coercivity, strong anisotropy, and smooth domain wall (DW) motion, because of the smoother interface compared with crystalline multilayers. For [CoSiB(6Å)/Pt (14Å)]N multilayers with N=3, 6, and 9, we studied the field-induced DW dynamics. The effective anisotropy constant K1 eff is 1.5×106 erg/cm3 for all the N values, and the linear increment of coercive field Hc with N gives constant exchange coupling J. By analyzing the field dependence of DW images at room temperature, a clear creep motion with the exponent μ=1/4 could be observed. Even though the pinning field Hdep slightly increases with N, the pinning potential energy Uc is constant (=35 kBT) for all the N values. These results imply that the amorphous [CoSiB/Pt]N multilayers are inherently homogeneous compared to crystalline multilayers. For N≤6, the pinning site density ρpin is less than 1000/μm2, which is about 1 pinning site per the typical device junction size of 30×30 nm2. Also, the exchange stiffness constant Aex is obtained to be 0.48×10-6 erg/cm, and the domain wall width is expected to be smaller than 5.5 nm. These results may be applicable for spin-transfer-torque magnetic random access memory and DW logic device applications. [ABSTRACT FROM AUTHOR]

The Fe/MgO/Fe magnetic tunnel junction with C modified interfaces has been studied based on the first principle density function theory method under a finite bias voltage for thin (five layers) and thick (ten layers) MgO barriers. Positive and negative tunneling magnetic resistance (TMR) ratios are obtained as a function of the interface structure. We found that the tunneling conductance is highly nonlinear for asymmetric systems with C at one side of the barrier, and even a sign reversal of the TMR as a function of the bias was found to be in agreement with experiments. [ABSTRACT FROM AUTHOR]

Materials with perpendicular magnetic anisotropy (PMA) have been intensively studied for high-density nonvolatile memory such as spin-transfer-torque magnetic random access memory with low switching current density and high thermal stability. Compared with crystalline PMA multilayers, considerable works have been done on amorphous PMA multilayers because the amorphous materials are expected to have lower pinning site density as well as smaller domain wall width. This study is an overview of the PMA properties of amorphous [CoSiB/Pt]N multilayers with varying N, where the energy contribution is changed from domain wall energy to magnetostatic energy around N=6. By measuring the field-induced domain wall motion, we obtain the creep exponent of μ=1/4. These results in the amorphous PMA multilayers of [CoSiB/Pt]N demonstrate possible potential as a free layer for PMA-based memory devices. [ABSTRACT FROM AUTHOR]

PbPdO2 is a new class of gapless semiconductors, which is extremely sensitive to external influences such as temperature, magnetic field, and carrier doping, because of their peculiar band structure. With varying temperature, a broad transition from a high-temperature metallic behavior to a low-temperature insulating behavior was observed at TMI=100 K in the electrical resistivity, which is related to the thermally assisted excitation near the Fermi level due to its gapless band structure. By doping 10% Co for Pd in PbPdO2, the number of hole charge carriers was increased by ten times, and the transition temperature was increased to TMI=150 K. When applying a magnetic field, a ferromagnetic component was found at low temperatures in the magnetization curves of both materials, in addition to diamagnetic background signals for PbPdO2 and paramagnetic background signals for PbPd0.9Co0.1O2. In the low temperature regime, the slope of magnetoresistance is negative, while it is changed into positive with a quadratic form at high temperatures. These results of magnetic properties identify a tendency of strong spin-orbit coupling in the gapless semiconducting compounds. [ABSTRACT FROM AUTHOR]

PbPdO2 is a new class of gapless semiconductors, which is extremely sensitive to external influences such as temperature, magnetic field, and carrier doping, because of their peculiar band structure. With varying temperature, a broad transition from a high-temperature metallic behavior to a low-temperature insulating behavior was observed at TMI=100 K in the electrical resistivity, which is related to the thermally assisted excitation near the Fermi level due to its gapless band structure. By doping 10% Co for Pd in PbPdO2, the number of hole charge carriers was increased by ten times, and the transition temperature was increased to TMI=150 K. When applying a magnetic field, a ferromagnetic component was found at low temperatures in the magnetization curves of both materials, in addition to diamagnetic background signals for PbPdO2 and paramagnetic background signals for PbPd0.9Co0.1O2. In the low temperature regime, the slope of magnetoresistance is negative, while it is changed into positive with a quadratic form at high temperatures. These results of magnetic properties identify a tendency of strong spin-orbit coupling in the gapless semiconducting compounds. [ABSTRACT FROM AUTHOR]

Saitoh et al. [Nature (London) 432, 203 (2004)] have reported the experimental result showing the interplay of a transverse domain wall with an electrical ac of megahertz-range frequencies. They observed a single peak of resistance in the frequency range and interpreted it with a nonadiabatic spin torque. It was argued that an ac current can induce a micrometer-range displacement of domain wall. We reconstructed the experiment in micromagnetic simulations considering the local nonzero nonadiabatic spin torque. We could not observe either an explicit single peak in the frequency-dependent resistance or an eventual displacement of domain wall by use of an ac. It indicates the local nonadiabatic torque is inappropriate to explain the experimental results of ac-induced domain wall motion. Other approaches such as the nonlocal nonadiabatic spin torque may be needed. [ABSTRACT FROM AUTHOR]

A systematic investigation of the magnetic and recording characteristics of CoPtCrO media with different Co grain magnetic anisotropy orientation dispersion (AOD) is performed. AOD is characterized by Δθ50 of the x-ray diffraction Co peak. AOD was systematically varied between 3.3° and 10.5° by varying the growth condition of Ru layer. With increasing AOD, more grain-boundary segregation occurs, resulting in reduced exchange coupling. Micromagnetic simulation and experimentally measured time dependence of coercivity indicate that magnetic switching of well-isolated Co particles is affected by exchange coupling strength as well as Co AOD. Higher coercivity, narrower switching field distribution, and good thermal stability are achieved with lower Co AOD. Reduced Co AOD leads to a substantial decrease of both transition jitter and dc noise. [ABSTRACT FROM AUTHOR]

We present switching characteristics of patterned submicrometer magnetic tunnel junction arrays containing NiFe and CoFe free layers. The resemblance of magnetization and magnetoresistance (MR) curves was studied by micromagnetic calculations and experimental measurements. Upon analyzing the MR transfer curves, the magnetic vortex and domain wall pinning effects on anomalous switching of each magnetic tunnel junction can be distinguished by remanent states. Data indicates that the low saturation magnetization of the free layer increases domain wall pinning and decreases trapped magnetization vortices. [ABSTRACT FROM AUTHOR]

GaMnN and Mg-codoped GaMnN films were grown in molecular beam epitaxy using a GaN single precursor. The structural, electrical, and magnetic properties were examined. The Mg-codoped GaMnN layers revealed room-temperature ferromagnetism. Codoping with Mg reduces the Mn incorporation, but increases the conductivity of the GaMnN films. At the same time, the saturation magnetization and coercivity have increased at room temperature. As this improvement was obtained with much reduced Mn concentration of ∼0.3%, the crucial role of the carriers for carrier-induced ferromagnetism in magnetic semiconductors is observed. [ABSTRACT FROM AUTHOR]

In this article, the effect of thermal fluctuations on switching field at short and long time scales have been investigated by micromagnetic simulation with the Langevin and the time-temperature scaling methods. When the film thickness and/or the aspect ratio are reduced, the switching field decreases substantially owing to the decrease of shape anisotropy and the increase of thermal fluctuation. In the soft magnetic film with a dimension of 0.4 µm × 0.2 µm × 1 nm, the calculated switching field at a pulse width of 10 ns is 32 Oe, but estimated retention time is less than 1000 s. In such a thermally unstable film, thermally activated switching of magnetization occurs by complex behaviors with creations and annihilations of small and slightly tilted magnetic clusters. [ABSTRACT FROM AUTHOR]

We show extensive Monte Carlo (MC) results on properties of thin films made of stacked XY triangular layers of atoms bearing Heisenberg spins. The film surfaces are frustrated due to antiferromagnetic in-plane interactions, while interior layers are ferromagnetic. We have included both the cohesive and magnetic interactions between neighboring atoms. These simultaneous magnetic and cohesive interactions are supposed to be the Lennard-Jones potential. Due to these interactions, the magnetic atoms move around their equilibrium positions (off-lattice model). We have carried MC calculations with varying surface antiferromagnetic exchange interaction. Depending on parameters the surface spin configuration can be noncollinear and film surfaces become magnetically disordered at a temperature lower than that of interior layers. Detailed results on other properties are shown and discussed. [ABSTRACT FROM AUTHOR]

This paper presents results of finite element analysis of induction heating problems considering temperature dependence of material characteristics. In this analysis, we have used the three dimensional finite element method in order to correctly express the induction heating coil's shapes and to make clear its effects on temperature distributions. The heat conducting problem and the eddy current problem are coupled and solved by using step-by-step calculations. [ABSTRACT FROM AUTHOR]

Effects of the shape anisotropy on the thermally activated spin relaxation have been investigated using the stochastic Landau-Lifshitz-Gilbert equation. The relaxation times of a noninteracting particle and a thin film were compared with each other. In a noninteracting particle, the relaxation time largely increased with the shape anisotropy when the damping constant was smaller than a certain critical value. In this study, the critical damping constant was 0.02. However, the effect of the shape anisotropy on the energy barrier was negligible in a thin film. All of these results can be explained from the effect of magnetostatic interaction that is enhanced by precession motion at low damping constant. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated the influence of the magnetic interactions on distribution of energy barrier and time dependent phenomena of magnetization by micromagnetic and Monte Carlo simulation. Calculation model; Results and discussion; Conclusions.

The dynamics of a magnetic domain wall (DW) under a transverse magnetic field Hy are investigated in two-dimensional (2D) Co/Ni microstrips, where an interfacial Dzyaloshinskii-Moriya interaction (DMI) exists with DMI vector D lying in +y direction. The DW velocity exhibits asymmetric behavior for ±Hy; that is, the DW velocity becomes faster when Hy is applied antiparallel to D. The key experimental results are reproduced in a 2D micromagnetic simulation, which reveals that the interfacial DMI suppresses the periodic change of the average DW angle φ even above the Walker breakdown and that Hy changes φ, resulting in a velocity asymmetry. This suggests that the 2D DW motion, despite its microscopic complexity, simply depends on the average angle of the DW and thus can be described using a one-dimensional soliton model. These findings provide insight into the magnetic DW dynamics in 2D systems, which are important for emerging spin-orbitronic applications. [ABSTRACT FROM AUTHOR]

The magnetotransport properties of Pb(Pd,Co)O2 and PbPdO2 thin films were investigated. In magnetoconductance curves, we observed a crossover between weak anti-localization (WAL) and weak localization (WL) depending on the annealing and Co doping in PbPdO2 thin films. For the Pb(Pd,Co)O2 case showing WAL signals, the ex-situ annealing weakens the Pd-O hybridization by stabilizing Co3+ states and generating Pd1+ states, instead of Pd2+, so that the spin-orbit coupling (SOC) strength is significantly reduced. It causes the dominant magnetotransport mechanism change from WAL to WL. This annealing effect is compared with the PbPdO2 case, which possesses WL signals. The annealing process stabilizes the oxygen states and enhances the Pd-O hybridization, and consequently the SOC strength is enhanced. Our experimental results are well explained by the Hikami-Larkin-Nagaoka theory in terms of two important physical parameters; SOC strength-related α and inelastic scattering length lϕ. [ABSTRACT FROM AUTHOR]

The magnetotransport properties of Pb(Pd,Co)O2 and PbPdO2 thin films were investigated. In magnetoconductance curves, we observed a crossover between weak anti-localization (WAL) and weak localization (WL) depending on the annealing and Co doping in PbPdO2 thin films. For the Pb(Pd,Co)O2 case showing WAL signals, the ex-situ annealing weakens the Pd-O hybridization by stabilizing Co3+ states and generating Pd1+ states, instead of Pd2+, so that the spin-orbit coupling (SOC) strength is significantly reduced. It causes the dominant magnetotransport mechanism change from WAL to WL. This annealing effect is compared with the PbPdO2 case, which possesses WL signals. The annealing process stabilizes the oxygen states and enhances the Pd-O hybridization, and consequently the SOC strength is enhanced. Our experimental results are well explained by the Hikami-Larkin-Nagaoka theory in terms of two important physical parameters; SOC strength-related α and inelastic scattering length lϕ. [ABSTRACT FROM AUTHOR]

We report construction of an acoustic superlensing using two dimensional membrane-based negative-density metamaterials. When two point sources separated by a distance of 1/17 of the wavelength are placed near to a surface of the metamaterial slab, well-resolved images are formed on the opposite surface across the slab. The mechanism for the subwavelength resolution is the surface wave stemming from negative density. Potential applications include acoustic imaging and sensing. [ABSTRACT FROM AUTHOR]

Electronic structures of Pb(Pd0.9T0.1)O2 (T=Mn, Co) spin gapless semiconductors have been investigated by employing soft X-ray absorption spectroscopy (XAS) and photoemission spectroscopy (PES). The valence states of Co and Mn ions are found to be mixed-valent (∼2.7) and tetravalent, respectively. The measured valence-band PES and O 1s XAS spectra show that both PbPdO2 and PbPd0.9Co0.1O2 are small-gap semiconductors. This finding is supported by the calculated band structures, obtained in the density functional theory with the modified Becke-Johnson potential (mBJ) scheme. This work also shows evidence for the existence of the phase separation in Mn-substituted PbPd0.9Mn0.1O2. [ABSTRACT FROM AUTHOR]

We report the transport properties of a dual MgO barrier magnetic tunnel junction (DMTJ) where a FeNiSiB layer was inserted in a CoFeB free layer. Upon post-deposition annealing at 330 °C, the tunneling magnetoresistance (TMR) ratio of the DMTJ with a hybrid CoFeB/FeNiSiB/CoFeB free layer reached 195% which is higher than the TMR ratio of 121% from the DMTJ with the single CoFeB free layer. The bias voltage dependence profile was more symmetric for the hybrid case. Boron depth profiling result suggests that the FeNiSiB layer dragged boron atoms more to it rather than letting them diffuse toward CoFeB/MgO interfaces, resulting in improved MTJ performances. [ABSTRACT FROM AUTHOR]

Spin wave attenuation in the layered [FeNi/Pt]6/FeNi thin films was investigated by the time-domain electrical measurement. The spin-wave waveform was detected with an asymmetric coplanar strip transmission line, as an induced voltage flowing into a fast oscilloscope. We report that the amplitude of a spin-wave packet was systematically changed by controlling the thickness of a platinum layer, up to a maximum change of 50%. The virtues of spin wave, ultrafast propagation velocity and non-reciprocal emission, are preserved in this manner. This means that the Pt layer can manipulate an arbitral power-level of spin-wave input signal (reliable attenuator). [ABSTRACT FROM AUTHOR]

Current-induced spin torque and magnetization dynamics in the presence of spin Hall effect in magnetic textures is studied theoretically. The local deviation of the charge current gives rise to a current-induced spin torque of the form (1-βM)×[(u0+αHu0×M)·∇]M, where u0 is the direction of the injected current, αH is the Hall angle and β is the non-adiabaticity parameter due to spin relaxation. Since αH and β can have a comparable order of magnitude, we show that this torque can significantly modify the current-induced dynamics of both transverse and vortex walls. [ABSTRACT FROM AUTHOR]

It is quite interesting to develop a multifunctional device using a single material with a simple structure. One of the possible candidates could be multiferroics, which are both ferroelectric and magnetic. By taking advantage of the strong spin-charge coupling, the electric field can control the magnetic polarization and the magnetic field can control the electric polarization. However, these multiferroics are not yet attractive for practical applications because none of the existing materials combine large and robust electric and magnetic polarizations at room temperature. Here, we report an unusual functional material showing a magnetic phase strongly coupled to an electric memory state at room temperature. An oxygen-vacant ZrO2 thin film generates bistable resistive switching between high-resistance (HR) and low-resistance (LR) states by applying external voltage, and it is ferromagnetic at the HR state but nonmagnetic at the LR state. This unique feature is applicable to unusual functional devices, such as electric-field-controlled magnetic data storage devices. [ABSTRACT FROM AUTHOR]

The effects of thickness asymmetry (Δt) on the dynamic magnetization switching of exchange-coupled trilayers are investigated in this study. Elliptical thin films that have lateral dimensions of 200×100 nm2 are considered. A significant difference in the dynamic switching behavior is observed depending on Δt. Both the switching field and the switching time decrease as Δt increases. A Fourier analysis of the magnetization oscillation, which is followed by the initial coherent rotation, shows multiple oscillation frequencies. This tendency is more pronounced at a larger Δt. The main oscillation frequency tends to increase with an increase in Δt. [ABSTRACT FROM AUTHOR]

The dynamic magnetization switching of a nanostructured exchange-coupled trilayer with a small thickness asymmetry is investigated by micromagnetic simulation. The magnetization switching initially occurs by coherent rotation, followed by magnetization oscillation. The switching time, which is about 9 ns at an applied field just above the switching field, is a factor of two longer than that observed for a single-layered thin film. A Fourier analysis of the magnetization oscillation shows multiple oscillation frequencies, the main frequency of which decreases as the applied magnetic field increases. [ABSTRACT FROM AUTHOR]

We investigated the magnetic and transport properties of Ni-doped TiO2 films grown by a sol-gel method with Ni concentrations from 1% to 8%. All the samples exhibited ferromagnetism at room temperature identified by optical magnetic circular dichroism along with magnetometer measurement. The microstructural and compositional analysis revealed Ni-rich regions with rather uniform background, indicating that at least two different sources contribute to the observed ferromagnetism. The Hall effect study showed that the carriers are electrons with density lower than 1018 cm-3 at room temperature, and no anomalous Hall effect has been observed due to the high resistivity of our samples. The observation of ferromagnetism in highly-resistive Ni-doped TiO2 films questions the carrier-mediated exchange interaction as an origin of ferromagnetism in this material. [ABSTRACT FROM AUTHOR]

We studied current-induced magnetic switching and excitations in structures comprising a free layer with in-plane magnetization traversed by a current with perpendicular-to-plane spin polarization. We derived analytical solutions from the Landau–Lifshitz–Gilbert equation including the spin-torque term, and compared them to numerical simulations within the single domain assumption. Taking into account the criterion of thermal stability, the magnetization switching in nanostructures of typical size below 100 nm comprising a perpendicular polarizer is found to require larger current density but to be much faster than with a longitudinal polarizer. Furthermore, a steady precession of magnetization can be generated in this geometry; those frequencies can be tuned from about 1 to 20 GHz by only changing the current without applying any external field. This opens a promising application as microwave sources. [ABSTRACT FROM AUTHOR]

We have studied the ex-situ annealing effects on the surface morphology and electrical transport of gapless semiconductors, PbPdO2 and Pb(Pd,Co)O2 thin films, with varying annealing temperature and time. The annealing process gives rise to better surface morphology in both samples. The optimal annealing conditions are obtained to be 650 °C and 12 h. On the other hand, the electrical properties are differently found for both samples. The electrical conduction is improved for PbPdO2 film by annealing, while it is lowered for Pb(Pd,Co)O2 film. The improvement of electrical conduction for PbPdO2 is well explained by the reduction of lattice imperfections of PdO droplets and Pd or O deficiencies, which is related with the hybridization between the Pd 4d and O 2p bands. However, this tendency is not applied for Pb(Pd,Co)O2 because of the trivalent Co state, which generates the monovalent Pd state, leading to the decrease of electrical conduction as a result of the reduction of Pd(4d)-O(2p) hybridization. [ABSTRACT FROM AUTHOR]

Free-standing micro- and nanoscale objects of single crystal silicon can be fabricated from silicon-on-insulator waters by lithographic patterning of resist, etching of the exposed top silicon, and removing the underlying SiO2 to lift-off the remaining silicon. A large collection of such objects constitutes a type of material that can be deposited and patterned, by dry transfer printing or solution casting, onto plastic substrates to yield mechanically flexible thin film transistors that have excellent electrical properties. Effective mobilities of devices built with this material, which we refer to as microstructured silicon (μs-Si), are demonstrated to be as high as 180 cm2V s on plastic substrates. This form of ‘top down’ microtechnology might represent an attractive route to high performance flexible electronic systems. [ABSTRACT FROM AUTHOR]

The effects of Mg codoping on the structural, electronic transport, and magnetic properties of GaMnN films are investigated. Mg was shown to compete with Mn for incorporation into the growing films at impingement, and to replace Mn. The partial replacement of Mn by Mg in GaMnN has resulted in an increase of conductivity of the region. The enhanced transport property due to the highly efficient dopant Mg resulted in a remarkable increase of the saturation magnetization, indicating an interaction between Mn and Mg for the carrier-mediated ferromagnetism. The increased carrier population by Mg codoping enabled a full mediation among the Mn atoms, and consequently, suppressed the paramagnetic rise in the temperature-dependent magnetization measurement. [ABSTRACT FROM AUTHOR]

GaMnN growth on GaAs (100) using a GaN single precursor via molecular beam epitaxy was undertaken. The grown layers revealed p-type conduction. It is confirmed that p-GaMnN reveals room temperature ferromagnetism with hysteresis loop having a coercivity of ∼100 Oe. The segregated phase showing a transition temperature of ∼200 K is assigned to Mn[sub 3]GaN, and which enhances the conductivity of the surrounding GaMnN region. As a consequence, the GaMnN layer with segregation revealed an anomalous Hall effect at room temperature proving magnetotransport in GaMnN phase. The enhanced conductivity of GaMnN by the highly conductive second phase also revealed the importance of the role of the free carriers in the carrier-mediated ferromagnetism. [ABSTRACT FROM AUTHOR]

We report a new class of three-dimensional topological insulators of transition metal doped Bi2Se3, TrxBi2Se3, and Bi2-xTrxSe3 (Tr = Cr, Fe, Cu) with x = 0.15, for the intercalation and substitution cases. With varying the doping atoms, a great variety of properties are observed in a single crystal form. The Cu-intercalated crystal shows superconducting behavior below 3 K, where the diamagnetic signal is found. The increase of carrier density at low temperature is likely to be responsible for the superconductivity. The magnetically doped case of the Fe-substituted Bi2Se3 exhibits dominance of ferromagnetic interactions, whereas the Cr-substituted Bi2Se3 favors antiferromagnetic interactions. From these results, we learn that the peculiar transport and magnetic properties of topological insulator Bi2Se3 are easily tunable by chemical doping elements, which change the Fermi energy and manipulate the charge carriers. [ABSTRACT FROM AUTHOR]

We have measured the temperature- and field-dependent magnetoresistance in an undoped AlGaN/GaN two-dimensional electron gas sample at temperatures below 10 K. Well-resolved Shubnikov-de Haas oscillations have been observed, as well as spin splitting at magnetic fields above 8 T. The amplitude of the oscillations has been used as a thermometer for the electron temperature, T[sub e], studies as a function of driving current have shown that under high applied electric fields the power input per electron follows a T[sub e][sup 4.4] dependence. Comparison with numerical modeling indicates that in this heterostructure, electron-acoustic phonon scattering via the screened piezoelectric interaction is the dominant energy-loss mechanism at low temperatures. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The perpendicular magnetic anisotropic properties of amorphous multilayers of [CoSiB/Pt]N are investigated as functions of the thickness of magnetic layers (tCoSiB = 4 and 6 Å) and the number of repeated bilayers (N = 3 ∼ 20). Even though the magnetization reversal process is dominated by the wall motion of magnetic domains rather than the nucleation for all the values of tCoSiB and N in our experiment, the changes of magnetic properties are strongly dependent on the tCoSiB and N values. The effective anisotropy constant for the 6 Å sample is K1eff = 1.2 × 106 erg/cm3, which is a factor of 6 larger than that for the 4 Å sample. The coercivity variations as a function of N are explained by the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling between the magnetic layers considering the balance of domain wall energy and magnetostatic energy. [ABSTRACT FROM AUTHOR]

A correction to the article "Simple tuning of carrier type in topological insulator Bi2Se3 by Mn doping," by Y. H. Choi and colleagues that was published in the February 22, 2013 issue is presented.

Bi2Te3 is a well-known thermoelectric material for room-temperature operations because it has a high Seebeck coefficient, and the charge carrier type is easily tunable. However, the carrier type of Bi2Se3 is not tunable, which is one of the weaknesses for the thermoelectric applications, in spite of its high Seebeck coefficient. Here, we report the tuning of charge carriers in Bi2Te3 from n type to p type by doping Mn into the Bi sites. The carrier type is n type up to the Mn doping level of 5% and changes to p type above 5% Mn doping. The temperature-dependent resistivity of Bi2-xMnxSe3 shows a metallic behavior for x < 0.05, while for x ≥ 0.05, it shows an upturn at low temperatures. This provides evidence that by Mn doping, the Fermi level is continuously tuned from the bulk conduction band to the bulk valence band. The Seebeck coefficient increases monotonically with increasing temperature, and the absolute values are same for both n- and p-type samples. This implies that Bi2Se3 is another candidate of high-temperature thermoelectric materials, like Bi2Te3, simply by Mn doping. [ABSTRACT FROM AUTHOR]

A correction to the article "Spin hall effect-driven spin torque in magnetic texture" that was published online in the December 1, 2011 issue is presented.

Electronic structures of Pb(Pd0.9T0.1)O2 (T=Mn, Co) spin gapless semiconductors have been investigated by employing soft X-ray absorption spectroscopy (XAS) and photoemission spectroscopy (PES). The valence states of Co and Mn ions are found to be mixed-valent (∼2.7) and tetravalent, respectively. The measured valence-band PES and O 1s XAS spectra show that both PbPdO2 and PbPd0.9Co0.1O2 are small-gap semiconductors. This finding is supported by the calculated band structures, obtained in the density functional theory with the modified Becke-Johnson potential (mBJ) scheme. This work also shows evidence for the existence of the phase separation in Mn-substituted PbPd0.9Mn0.1O2. [ABSTRACT FROM AUTHOR]

We investigated the magnetic and transport properties of Ni-doped TiO2 films grown by a sol-gel method with Ni concentrations from 1% to 8%. All the samples exhibited ferromagnetism at room temperature identified by optical magnetic circular dichroism along with magnetometer measurement. The microstructural and compositional analysis revealed Ni-rich regions with rather uniform background, indicating that at least two different sources contribute to the observed ferromagnetism. The Hall effect study showed that the carriers are electrons with density lower than 1018 cm-3 at room temperature, and no anomalous Hall effect has been observed due to the high resistivity of our samples. The observation of ferromagnetism in highly-resistive Ni-doped TiO2 films questions the carrier-mediated exchange interaction as an origin of ferromagnetism in this material. [ABSTRACT FROM AUTHOR]