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CePdSi3 with H // [100] exhibits multiple metamagnetic transitions. Since there is no frustration in this system, it is suggested that the origin of the multiple metamagnetic transitions is the inf...

Specific heat and small-angle neutron scattering measurements have been performed on the superconductor β-PdBi2. Whereas models with a uniform gap do not yield an adequate description of the temper...

One of the consequences of antisymmetric spin–orbit interactions due to a lack of inversion symmetry are unusually large upper critical fields observed in heavy-electron superconductors. The upper ...

We reconstruct a magnetic phase diagram of the non-centrosymmetric CePtSi3 through magnetization measurements for H || [100]. The observed magnetization curves show four newly found anomalies in ad...

We have investigated magnetic properties of the rare-earth based intermetallic compound Yb3Ni11Ge4.63 (YNG), where Yb3+ ions form a breathing-kagome lattice. Single-site 4f electron wavefunctions o...

In this study, the temperature dependence of the elastic constants C11, C33, CE = (C11 − C12)/2, C66, and C44 of the iron-based superconductor Ba(Fe1−xCox)2As2 (\(0 \leqq x \leqq 0.245\)) have been...

We have investigated uniaxial and hydrostatic pressure effects on superconductivity in Fe1.07Te0.88S0.12 through magnetic-susceptibility measurements down to 1.8 K. The superconducting transition temperature Tc is enhanced by out-of-plane pressure (uniaxial pressure along the c-axis); the onset temperature of the superconductivity reaches 11.8 K at 0.4 GPa. In contrast, Tc is reduced by in-plane pressure (uniaxial pressure along the ab-plane) and hydrostatic pressure. Taking into account these results, it is inferred that the superconductivity of Fe1+yTe1-xSx is enhanced when the lattice constant c considerably shrinks. This implies that the relationship between Tc and the anion height for Fe1+yTe1-xSx is similar to that applicable to most iron-based superconductors. We consider the reduction of Tc by hydrostatic pressure due to suppression of spin fluctuations because the system moves away from antiferromagnetic ordering, and the enhancement of Tc by out-of-plane pressure due to the anion height effect on Tc., Comment: 5 pages, 4 figures. This paper has been accepted for publication in J. Phys. Soc. Jpn

We present a new model compound of an S = 1/2 frustrated system with ferromagnetic interaction composed of verdazyl radical β-2,3,5-Cl3-V. The ab initio molecular orbital calculation indicates the formation of an S = 1/2 trellis lattice in which zigzag chains and ladders with ferromagnetic rung interaction are two-dimensionally coupled. We observe a field-induced successive phase transition and an unconventional change in the magnetization curve near the saturation field, accompanied by T2 dependence on the magnetic specific heat. A two-dimensional spin-nematic state attributed to the ferromagnetic rung interactions is a possible candidate for the ground state in high-field regions.

Filled skutterudites show various interesting physical properties, such as unconventional superconductivity, anomalous magnetism, metal–insulator transition, heavy fermion behavior and so on. We have investigated the multipole ordering state of SmRu 4 P 12 by ultrasonic measurements under extreme conditions of low temperature, high pressure and high magnetic field by pulsed method, so far. Recently, the angle dependence of the elastic constant has been measured. The elastic constant shows interesting and peculiar angle dependence below the metal–insulator transition temperature in the magnetic field. It will enable us to reveal characteristic multipole ordered state in SmRu 4 P 12 . In this paper, we will report recent status of the multipole ordered state of SmRu 4 P 12 , and discuss the recent results of our elastic constant measurements and the relation to the octupole ordering scenario proposed for this system.

We have reported curious behavior found in the elastic constant associated with the Metal–Insulator (M–I) transition and the successive phase transition in SmRu 4 P 12 . To explain characteristic properties of SmRu 4 P 12 , we focus our attention on two features; (1) an elastic softening appears below M–I transition and (2) the phase boundary between phases II and III is indistinct. Symmetry consideration and a phenomenological theory base on it show that particular couplings among the dipole as the order parameter for phase III, the octupole moment as that for phase II and the elastic strain, a part of which is allowed only in T h symmetry, are responsible for strange phenomena in SmRu 4 P 12 .

Magnon excitations have been investigated for PrMnO 3 showing an A -type antiferromagnetic ordering and TbMnO 3 forming a long-period spin ordering by inelastic neutron scattering. Combined with a ...

We have studied the origin of the successive phase transitions in filled skutterudite SmRu 4 P 12 based on the results of elastic constant measurements. The temperature dependence of the elastic constants shows a sharp drop at the metal–insulator (M–I) transition of T MI = 16.5 K in a zero field. The successive transition at T N = 14 K is indistinct in a low field. The anomaly at T MI disappears with increasing field. A clear softening toward T N appears in the elastic constants in a high magnetic field. This result suggests a breakdown of the time reversal symmetry in the temperature range between T MI and T N . Such a breakdown is considered to be due to the coupling between the dipole moment and the octupole moment, which is allowed only in T h symmetry.

The magnetic structure of the antiferromagnetically ordered state of a quasi-one-dimensional conductor β-Na 0.33 V 2 O 5 below T N =24 K was examined by neutron diffraction. The presence of magnetic Bragg reflections at ( h , k ±1/6,0), h + k =odd below T N indicates that the amplitudes of the magnetic moments at the V sites in three types of V–O chains are modulated with a period of 3 b along the chain direction (∥ b ). On the other hand, it was confirmed that the lattice modulation along the b direction occurs at ∼244 K and at ∼131 K with a period of 2 b and 6 b , respectively. Although the latter structural transition had been attributed to a “charge ordering” transition, which would result in a charge disproportionation in the V 3 d orbitals with a period of 6 b , the 3 b periodicity in the amplitude of magnetic moments strongly suggests that the charge disproportionation occurs with a period of 3 b , not 6 b . The 6 b lattice modulation developing below 131 K is therefore attributed to an instability...

Heating by less than 10°C of heavy water was observed at room temperature upon the propagation of acoustic waves of 6 MHz with intensity of about 2 W/cm 2 during the scanning of a magnetic field from 800 to 1000 mT. A control experiment with light water did not show the heating. As a quantitative explanation of this heating, the “spin-flip phonon maser” action of deuterons due to the thermal Raman process of spin-phonon coupling is considered. Good agreement with the experimental result was obtained. The 6 MHz acoustic waves induce the pumping transitions of the nuclear spin system.

The longitudinal and transverse elastic constants of polycrystalline SmRu 4 P 12 have been measured as a function of temperature in the magnetic field up to 12 T. The transverse elastic constant shows a weak softening toward low temperatures. Both longitudinal and transverse elastic constants show a large anomaly below the metal–insulator transition T MI = 16 K. These elastic anomalies indicate the ground state of the crystalline electric field multiplet to be Γ 8 , and that the quadrupole ordering is responsible for this metal insulator transition. The successive anomalies of SmRu 4 P 12 have been clearly observed by ultrasonic measurements. An elastic anomaly was found at T * , which is 14 K in the absence of a magnetic field. T MI increases and T * decreases under the application of the magnetic field. The anomaly at T * is markedly enhanced by the application of a magnetic field.

The most significant structural feature of the A -site ordered manganese perovskites, R BaMn 2 O 6 , is that the MnO 2 square sublattice is sandwiched by two types of rock-salt layers, R O and BaO,...

A turbulent swirling flow is studied with the aid of a variational method. The mean-flow field is expressed by the mean vorticity proportional to its curl. The total axial flux and total helicity per unit length are introduced to characterize the swirling flow, and the condition for the reversal of the axial flow near the center of flow is obtained. On this basis, the helicity injection is discussed in the light of the control of the onset of flow reversal in a turbulent swirling flow. Reference is also made to a cylindrical jet in relation to a swirling laboratory jet and an accretion-disk jet.

For the paramagnetic insulating phase in the metal-ordered manganite YBaMn2O6, the so-called CE-type of charge/orbital ordered state was observed within the monoclinic ab-plane, which is most commonly observed for the ordinary half doped manganites. However, TEM revealed a 4-fold periodicity along the c-axis, suggesting a new stacking pattern, where planes of the CE-type are built up according to the sequence [aabb...]. Interestingly, when th system enters into the antiferromagnetic state, this stacking pattern changes into [aaaa...] or [abab], suggesting close interplay between spins and orbitals. These features are discusses in terms of inherent structural alternation, i.e., the Y/Ba order along the c-axis.

New metal-ordered manganites RBaMn_{2}O_{6} have been synthesized and investigated in the structures and electromagnetic properties. RBaMn_{2}O_{6} can be classified into three groups from the structural and electromagnetic properties. The first group (R = La, Pr and Nd) has a metallic ferromagnetic transition, followed by an A-type antiferromagnetic transition in PrBaMn_{2}O_{6}. The second group (R = Sm, Eu and Gd) exhibits a charge-order transition, followed by an antiferromagnetic long range ordering. The third group (R = Tb, Dy and Ho) shows successive three phase transitions, the structural, charge/orbital-order and magnetic transitions, as observed in YBaMn_{2}O_{6}. Comparing to the metal-disordered manganites (R^{3+}_{0.5}A^{2+}_{0.5})MnO_{3}, two remarkable features can be recognized in RBaMn_{2}O_{6}; (1) relatively high charge-order transition temperature and (2) the presence of structural transition above the charge-order temperature in the third group. We propose a possible orbital ordering at the structural transition, that is a possible freezing of the orbital, charge and spin degrees of freedom at the independent temperatures in the third group. These features are closely related to the peculiar structure that the MnO_{2} square-lattice is sandwiched by the rock-salt layers of two kinds, RO and BaO with extremely different lattice-sizes., Comment: 5 pages, 4 figures, submitted to J. Phys. Soc. Jpn

We have grown single crystals of LSMO(327) for x =0.35 and x =0.40 and investigated the elastic properties systematically, together with the electrical resistivity, magnetoresistance and magnetizat...

The 4f crystalline electric field (CEF) of the Pr3+ ion of PrPt2Cd20 with a cubic crystal structure has been studied by measuring its high-field magnetization up to 45 T, specific heat in a wide te...

The coexistence of antiferromagnetism and superconductivity in the hybrid ruthenate-cuprate RuSr 2 YCu 2 O 8 synthesized under high pressure has been confirmed by means of powder neutron diffraction and resistivity measurements. The Ru moments are antiferromagnetically ordered at about 149 K and Ru spins can be aligned by applying a magnetic field, suggesting that the system gradually changes from antiferromagnetism to ferromagnetism. However, the superconductivity in the compound persists even at H =9 T. This indicates the coexistence of ferromagnetism and superconductivity under a high magnetic field.

Comprehensive neutron-powder diffraction and Rietveld analyses were carried out to clarify the relation between the crystal and magnetic structures of La2-2xSr1+2xMn2O7 (0.30 =< x =< 0.50). The Jahn-Teller (JT) distortion of Mn-O6 octahedra, i.e., the ratio of the averaged apical Mn-O bond length to the equatorial Mn-O bond length, is Delta_JT=1.042(5) at x=0.30, where the magnetic easy-axis at low temperature is parallel to the c axis. As the JT distortion becomes suppressed with increasing x, a planar ferromagnetic structure appears at x =< 0.32, which is followed by a canted antiferromagnetic (AFM) structure at x =< 0.39. The canting angle between neighboring planes continuously increases from 0 deg (planar ferromagnet: 0.32 =< x < 0.39) to 180 deg (A-type AFM: x=0.48 where Delta_JT=1.013(5)). Dominance of the A-type AF structure with decrease of JT distortion can be ascribed to the change in the eg orbital state from d3z^2-r^2 to dx^2-y^2.

Thermal expansion and magnetostriction both in the a b -plane and along the c -axis of double-layered perovskite manganite (La 1- z Pr z ) 1.2 Sr 1.8 Mn 2 O 7 ( z =0, 0.2, 0.4 and 0.6) single crystals have been measured as a function of temperature and magnetic field. The anomalous lattice distortion and the giant magnetostriction associated with the CMR were observed near the PI to FM transition temperature T c . These findings indicate that the PI to FM transition and the CMR near T c are not associated with the anisotropic lattice striction concerning the static John–Teller effect but with the negative volume striction related to the delocalization of polarons to itinerant carriers.

We demonstrate that the half-doped bilayer manganite La_{1}Sr_{2}Mn_{2}O_{7} exhibits CE-type charge-ordered and spin-ordered states below $T_{N, CO}^A = 210$ K and below $T_{N}^{CE} \sim 145$ K, respectively. However, the volume fraction of the CE-type ordering is relatively small, and the system is dominated by the A-type spin ordering. The coexistence of the two types of ordering is essential to understand its transport properties, and we argue that it can be viewed as an effective phase separation between the metallic $d(x^{2}-y^{2})$ orbital ordering and the charge-localized $d(3x^{2}-r^{2})/d(3y^{2}-r^{2})$ orbital ordering.