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Double perovskites such as Sr2CrReO6 attract great scientific attention owing to their high Curie temperatures (TC ≥ 550 K) as well as large magnetoresistances. However, both the specific physical mechanism of high TC and magnetic ground state in Sr2CrReO6 remain ill‐defined. In order to clarify and understand these issues, we studied its critical phase transition characteristics using critical behavior analysis. We found that the obtained critical exponents (β = 1.115 and γ = 2.224) are quite different from any traditional universality class. The abnormal critical behavior implies that at the quantum critical point, Sr2CrReO6 exists a strong competition among several magnetic interactions. By analyzing their effective critical exponents, we show that the double perovskite Sr2CrReO6 is really an ordered and homogeneous ferromagnet. With the help of Takahashi's theory, the nature of ferromagnetism in Sr2CrReO6 is confirmed to be localized instead of itinerant. The results of this research will provide new insights into the origins of high TC as well as the magnetic ground state in this double perovskite. [ABSTRACT FROM AUTHOR]

In an effort to explore new electronic devices with multiple functionalities, there are numerous studies of depositing perovskite oxides on flexible substrates to replace rigid silicon‐based wafer in device applications. In this study, the growth of pseudocubic SrRuO3 single‐crystal thin film on a transparent and flexible muscovite is established. The experimental results confirm that the Curie temperature TC and the magnetic properties can be effectively tuned via the mechanical strain due to the facilitation of flexible substrate. It is found that the tensile strain increases while the compressive strain decreases the spontaneous magnetization for the thin film suffering the same ±0.24% strain. Based on the study of critical behavior, the critical exponents β = 0.543(19) and γ = 1.262(1) with the critical temperature TC = 159.04(5) K and TC = 159.10 K, respectively, are obtained by the modified Arrott plot. The set of critical exponents matches well with Widom scaling relation and the scaling equation, indicating these critical exponents are intrinsic for SrRuO3 thin films. Moreover, it is achieved that the SrRuO3 thin films exhibit a long‐range interaction coupled with 3D‐Heisenberg type. [ABSTRACT FROM AUTHOR]

The magnetic and electronic transport properties of the lightly doped SrRu1-x Fex O3 (x ≤ 0.15) have been studied. All the samples show a paramagnetic-ferromagnetic phase transition and hysteresis effect. With the increase of Fe, the temperature of magnetic phase transition decreases but coercive field increases indicting the existence of antiferromagnetic interaction and magnetic-crystalline anisotropy. In low temperature, all the doping samples exhibit an insulating behavior while metal feature appears only at x ≤ 0.10 samples. The induced disorder suppresses the itinerant property of Ru 4d electron due to Fe random occupation. As a result, the ferromagnetism is weakened and metal-insulator transition is suppressed. [ABSTRACT FROM AUTHOR]

The electronic transport and magnetism in half-doped Nd0.50Ca0.25Sr0.25MnO3 manganites have been investigated. Contrary to general half-doped system, it only displays a paramagnetic-ferromagnetic phase transition associated with an insulator-metal transition instead of with any features of charge ordering. With the decrease of temperature, an electronic phase separation and spin glass state occur in low temperature. We suggest that the A-site cation disorder induced by the size mismatch between Sr2+ ion and Ca2+ ion is mainly responsible for this phenomenon. [ABSTRACT FROM AUTHOR]

The structural, Hall effect, electronic transport, and magnetic properties of Ge0.96−xBixFe0.04Te epitaxial thin film as prepared by pulsed laser deposition technique were reported. X-ray diffraction patterns including linear scans and phi scans confirmed that all films are high quality epitaxy and crystallinity. With the substitution of high valence Bi for Ge element, we found that the previous carriers of hole were changed to electron, which was testified by the negative slopes obtained from the measurements of Hall effect under different temperatures. The electronic transports show a typical semiconductor behavior and can be understood by the small polaron hopping model because the lattice distortions increase the electron-phonon interaction. An obvious ferromagnetic properties occur in the high Bi-doping Ge0.64Bi0.32Fe0.04Te rather than in that with low Bi-doping concentration, indicating that the ferromagnetic establishment is entirely dependent on carrier's transmissions. The first-principles calculation performed on this system also reveals that the ferromagnetic state exactly exists in the present n-type diluted magnetic semiconductors with Bi co-dopants. [ABSTRACT FROM AUTHOR]

In this paper, we present a new calculation method of magnetic entropy in an arbitrary second-order ferromagnetic phase transition system. Based on the Arrott-Noakes relation (H/M)1/γ = (T-TC)/TC+(M/M1)1/β, the Gibbs energy can be rewritten as a new form where the critical exponents are naturally included. Correspondingly, the magnetic entropy (SM) is presented as: . Thus, the magnetic entropy change (ΔSM) can be deduced as which is consistent exactly with the previous report [V. Franco et al., Appl. Phys. Lett. 89 (2006) 222512]. In addition, the conventional calculation method of magnetic entropy can be treated as a particular form of this calculation method. Furthermore, the obtained magnetic entropy change from experimental measurement are consistent with the theoretical value deduced from the present method. [ABSTRACT FROM AUTHOR]

Abstract: The dependence of magnetization M on temperature T and the applied magnetic field H were measured for the half-doping manganite Nd0.5Sr0.25Ca0.25MnO3. The M(T) curve exhibits that a paramagnetic (PM)–ferromagnetic (FM) phase transition occurs around 174 K. The PM–FM phase transition is considered to be a second-order phase transition due to the absence of hysteresis on its heating and cooling M(T) curves. Moreover, the second-order phase transition can be testified with the positive slope in Arrott plots. However, the scaling analysis of magnetic entropy change exhibits that ΔS M (T) curves do not collapse into a single universal curve, indicating that the observed PM–FM phase transition is not an authentic second-order phase transition. Due to the appearance of short-range FM coupling in PM region, the PM–FM phase transition at 225 K > T > 188 K is a first-order phase transition. The second-order phase transition only occurs at T < 188 K. When the magnetic field is increased above 1.5 T, the first-order phase transition can be converted into the second-order phase transition. The results shows that the magnetic entropy change scaling is an effective method to determine the nature of the PM–FM phase transition. [Copyright &y& Elsevier]

Abstract: In this paper, we have studied the magnetic and magnetocaloric properties of the perovskite manganite Pr0.55Sr0.45MnO3. It shows a sharp paramagnetic–ferromagnetic phase transition at 291K and possesses a moderate magnetic entropy change near room temperature. In addition, a large relative cooling power (143.64J/kg) and a wide temperature range (84K) have been found in this material. Compare with the Landau model, we find that the itinerant electrons mainly contribute the larger magnetic entropy change at paramagnetic region. [Copyright &y& Elsevier]

Abstract: The magnetic behavior and electronic transport in the half-doped manganite Nd0.5Ca0.25Sr0.25MnO3 have been investigated. The critical exponents are studied by using isothermal magnetization methods. The results show that the paramagnetic–ferromagnetic transition is second order and the magnetic interaction is satisfied with the prediction of three-dimensional Heisenberg model. The electronic transport belongs to the percolation mechanism. These findings demonstrate that the critical behavior of the magnetic transition and conductivity for manganites are related to Mn-site ordering degree. [ABSTRACT FROM AUTHOR]

Abstract: The magnetism and electronic transport properties in the manganites have been studied. The doped sample provides a good system to detect the impurity effect in charge ordering materials due to a fixed ratio of . We find that the induced ferromagnetism stems from the exchange couple between the magnetic impurity and Mn element. The local charge ordering phase forms an antiferromagnetic coupling whereas its intensity weakens with the decrease of temperature. In the high temperature region, the electronic transport occurs in the variable-range hopping manner. [Copyright &y& Elsevier]

Abstract: The magnetic phase transition and insulating-metal phase transition in the charge ordering (CO) Nd0.51Ca0.49Mn0.98Cr0.02O3 system have been studied. From the magnetization and resistivity measurements, a considerable instability is observed in the temperature region upon thermal cycle. In the thermal hysteresis region, both antiferromagnetic (AFM) and paramagnetic (PM) phases transform into ferromagnetic (FM) phase as the temperature decreases, thus the strong ferromagnetism emerges in the system. The origin of the instability should be attributed to the strain relaxation in the interfacial region. Interestingly, due to the growing FM interaction, the AFM coupling becomes weakened rather than strengthened at low temperatures. [Copyright &y& Elsevier]

Abstract: The magnetic and transport properties in the perovskite Sr1− x La x Fe1− x Mn x O3 have been explored. As x rises, the systemic ferromagnetism increases gradually and cluster-spin-glass state occurs in the low-temperature region. For 0.3⩽x⩽0.7, the ferromagnetic phase separation from the paramagnetic phase was observed from the results of electron-spin-resonance measurement. Although all samples show a semiconducting behavior, their transport properties are dominated by two different mechanisms, namely, the electronic transport of x⩽0.5 samples is realized by thermal activation but the variable-range hopping is applied in x⩾0.7 ones. The different transport mechanism can be understood from the Mn/Fe ions interaction. [Copyright &y& Elsevier]

Double perovskites such as Sr2CrReO6 attract great scientific attention owing to their high Curie temperatures (TC ≥ 550 K) as well as large magnetoresistances. However, both the specific physical mechanism of high TC and magnetic ground state in Sr2CrReO6 remain ill‐defined. In order to clarify and understand these issues, we studied its critical phase transition characteristics using critical behavior analysis. We found that the obtained critical exponents (β = 1.115 and γ = 2.224) are quite different from any traditional universality class. The abnormal critical behavior implies that at the quantum critical point, Sr2CrReO6 exists a strong competition among several magnetic interactions. By analyzing their effective critical exponents, we show that the double perovskite Sr2CrReO6 is really an ordered and homogeneous ferromagnet. With the help of Takahashi's theory, the nature of ferromagnetism in Sr2CrReO6 is confirmed to be localized instead of itinerant. The results of this research will provide new insights into the origins of high TC as well as the magnetic ground state in this double perovskite. [ABSTRACT FROM AUTHOR]

Highlights: [•] Critical behaviors of half-doped Pr0.5Sr0.5 . [•] Hybridization between Co 3d orbits with O 2p states. [•] The long-range ferromagnetic interaction. [•] Scaling analysis. [ABSTRACT FROM AUTHOR]

Abstract: Critical behavior of the single-layered Sr2IrO4, which exhibits weak ferromagnetism in the ab plane, is investigated by the bulk magnetization study. Critical exponents and with the critical temperature T C =230.8±0.9 are obtained by the Kouvel–Fisher method, and is generated by the critical isotherm analysis at T C =231K. The obtained critical exponents of Sr2IrO4 are close to prediction of the theoretical model with (where d is the partial dimensionality and n is the spin dimensionality), which indicates one-dimensional ferromagnetic interaction in the two-dimensional layered material. On the other hand, the critical exponents lie between the prediction of long-range and short-range models, indicating that the short-range Heisenberg interaction alone cannot totally describe the critical behavior. It is suggested that the Dzialoshinsky–Moriya interaction caused by rotation of the octahedra and the symmetric anisotropy result into a lower spatial short-range interaction, which competes with the long-range interaction caused by expansion of 5d orbits. [Copyright &y& Elsevier]

Abstract: In this paper, the reason for choosing dopant Dy with large magnetic moment in La0.67-xDyxSr0.33MnO3 is to investigate how the magnetic structure of the system changes with Dy content increasing. It is found that all samples () undergo the transition from paramagnetism to ferromagnetism at TC. When TTC are determined by the phase separation for x=0.2 and by the Dy–O–Dy in La–O plane for x=0.3, respectively. The large magnetoresistance is caused by the sum of the applied and internal magnetic field. [Copyright &y& Elsevier]

Abstract: The magnetic entropy around the paramagnetic–ferromagnetic (PM–FM) phase transition temperature has been investigated for chromium based spinel CdCr2Se4. It is found that magnetic entropy changes are generated by the spin–lattice coupling, which can be easily modulated by the external magnetic field. The electron paramagnetic resonance (EPR) study proves the existence of the spin–lattice coupling above , and reveals the stronger coupling at . In addition, the variation of the micro-structure due to the spin–lattice interaction has been observed around from the measurement of the low-temperature X-ray diffraction. [ABSTRACT FROM AUTHOR]