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We studied the dependence of the electronic specific heat Cel/T on the magnetic field up to H = 8 T in a dilute quadrupolar compound Pr0.05La0.95Pb3 with a non-Kramers Γ3 doublet in the crystal-ele...

Magnetic studies were performed on PrPd2Si2 single crystals which crystallize in the tetragonal ThCr2Si2-type structure. The temperature dependence of the magnetic susceptibility indicates that the compound orders antiferromagnetically at temperatures below T N = 3.2 K. The transition was confirmed by specific heat measurements. Magnetization measurements at fields up to 18 T show that the easy magnetization direction is the [100] direction in the basal plane. In the magnetization process, five or four metamagnetic transitions appear; the process is a five (four)-step metamagnetic one. The [110] magnetization process is a three-step one. A strong magnetic anisotropy between the [100] and [110] directions is observed within the basal plane for high magnetic fields. Along the hard magnetization direction of the c-axis, a metamagnetic transition appears. The B [100] − T phase diagram was constructed. A magnetic anisotropy between the [100] and [001] directions is also strong. These behaviors are discussed based on an analysis of crystalline field effects.

The measurements of the electrical resistivity ρ and the thermopower S of single crystal EuCo2P2 have been performed at temperatures from 1.5 to 300 K under hydrostatic pressures up to 3 GPa and in magnetic fields up to 10 T. The temperature dependences of ρ and S show drastic changes at a critical pressure Pc, which indicates a large modification of the electronic structure around the Fermi level due to the valence transition from Eu to Eu. In the low-pressure phase with magnetic Eu and nonmagnetic Co, the magnetic field dependences of ρ and S show sudden decrease at B ≈ 7 T, implying a metamagnetic transition. On the other hand, no drastic change in ρ(B) and S(B) curves is observed in the high-pressure phase with nonmagnetic Eu and magnetic Co.

Magnetic characteristics of a DyPd2Si2 single crystal with the ThCr2Si2-type structure have been studied from measurements of magnetic susceptibility (T) and magnetization M(B). It was found that DyPd2Si2 orders antiferromagnetically below TN = 9.2 K with the basal-plane [100] axis being the easy magnetization direction at high magnetic fields. Upon increasing magnetic field, the [100] magnetization curve exhibits at least six metamagnetic transitions at 0.2, 1.8, 3.0, 3.7, 4.2 and 6.1 T before reaching the saturation magnetization Ms = 10 B. Five metamagnetic transitions were detected on decreasing fields. For the [110] magnetization process, three metamagnetic transitions were evidenced. In contrast, the M(B) curve along the [001] axis, which is the hard magnetization direction, displays no metamagnetic transition; it shows a monotonous increase with a concave curvature up to 18 T. Finally, we constructed a comprehensive B100-T magnetic phase diagram consisting of six magnetic ordered phases.

The pressure dependence of resistivity for the checkerboard-type charge-ordered (CO) molecular conductor $\ensuremath{\beta}\text{\ensuremath{-}}{(meso\text{-DMBEDT-TTF})}_{2}{\text{PF}}_{6}$ has been investigated. Under the low pressure of 0.6 kbar, the temperature of resistivity minimum $({T}_{\text{min}})$ falls from 90 K at an ambient pressure to 67 K, and after the resistivity has been increased, the superconducting (SC) transition is observed at 4.6 K. By applying magnetic field, the SC state is suppressed and the large positive magnetoresistance (MR) is demonstrated below ${T}_{\text{min}}$ in the CO state. Since the positive MR was observed even in the metallic state under high pressures, the summarized pressure-temperature $(P\ensuremath{-}T)$ phase diagram reveals that the SC state neighbors to the CO-insulating and charge-fluctuated metallic states.

EuSnP shows an antiferromagnetism below T N = 21 K , in which two metamagnetic transitions were observed with applying magnetic field along both the directions parallel and perpendicular to the c -axis of tetragonal structure. In addition, entropy released up to T N was only ∼ 75 % of R ln 8 which is the value of entropy expected from Eu2+ state. These might bring about novel antiferromagnetic ground state with noncollinear configuration of Eu2+ moments.

We measure the temperature dependence of the nonlinear susceptibility χ3, which reflects the fluctuation of quadrupolar moments, in Pr0.05La0.95Pb3 with a Γ3 non-Kramers doublet in the crystal-electric-field ground state to provide evidence of the quadrupolar Kondo effect. Non-Fermi liquid behavior of χ3 with a \(-\ln T\) dependence is detected in the [100] and [110] directions below \(T\approx 2.5\) K, suggesting the screening of quadrupolar moments. In contrast, χ3 in the [111] direction becomes constant below \(T\approx 3\) K. The observed features indicate that a low-lying Γ3 doublet plays a crucial role in the anomalous properties of PrxLa1-xPb3.

X-ray diffraction measurements on Ce2Fe17 have been performed in the temperature range from 8 to 300 K at the magnetic fields up to 5 T . The thermal expansion curves along the principal axes for antiferromagnet and ferromagnet Ce2Fe17 are presented. A distinct lattice expansion was observed simultaneously with the metamagnetic transition. This suggests that the hybridization between Fe 3d- and Ce 4f-electrons in Ce2Fe17 is suppressed by the application of magnetic field.

Thermal variations of magnetization under various magnetic fields and magnetization processes at various temperatures have been studied on a HoRh2Si2 single crystal compound. Three anomalies at TN1=29.1 K, Tt=27.3 K and TN2=12.0 K exist at low field in the thermal variation. The thermal dependence of M/B and the magnetization change drastically with magnetic field. Step-like metamagnetic processes appear along the all directions below TN2; two-step ones appear along the [001] and [100] directions, and a one-step one appears along the [110] direction. For TN2

High field magnetization measurement were performed up to 45 T using a long pulse magnet on a GdPd2Si2 single crystal compound having the tetragonal ThCr2Si2-type crystal structure and an antiferromagnetic ordering of TN=16.7 K. The magnetization processes are almost typical antiferromagnetic ones with a weak magnetic anisotropy though small anomalies exist in the processes. The magnetization saturates 7 μB/f.u. above Bs=32 T. The B001-T and B100-T magnetic phase diagrams were constructed. There are three phases, the phase I, II and III, under non-magnetic field in the ordered state for both diagrams. The field-induced phase, phase IV, appears below the paramagnetic phase by the [100] magnetic field, B100, which is accompany with a re-entrant behaviour. The B100 makes the phase II be stable and the phase I and III be instable. These strange behaviours indicate the direction of the magnetic moment changes in each phase.

Magnetic characteristics have been studied for a TbPd 2 Si 2 single crystal from measurements of magnetic susceptibility, high field magnetization, and specific heat. The antiferromagnetic ordering below T N =15 K has been confirmed. The easy magnetization direction is the [110] direction in the basal plane at high magnetic fields. The [110] magnetization is saturated above 24 T and reaches M s =9.0 µ B . Multistep metamagnetic behaviors appear in the basal plane magnetization processes. A one-step metamagnetic transition appears in the [001] magnetization process and persists up to 28 K above T N . Strong magnetic anisotropy is observed between the [110] and [100] directions for high fields, and between the [001] and directions in the basal plane. Magnetic phase diagrams are constructed, in which there are four magnetic ordered phases. The main features of anisotropic magnetic behaviors are almost explained by crystalline electric field effects.

Magnetic and specific heat measurements have been performed on a GdPd2Si2 single crystal compound having the tetragonal ThCr2Si2-type crystal structure. Specific heart shows two λ-type anomalies at TN=16.7 K, T1=12.3 K and a small hump with hysteresis at T2=6.8 K; there are three phases below TN. The magnetic entropy of Rln6 is released below TN. The temperature dependence of magnetic susceptibility shows a very peculiar behaviour. With decreasing temperature, the magnetic susceptibility along the [001] direction increases through a small kink at TN down to T1 where a clear cusp is seen, decreases rapidly below TN, then shows an upturn and a clear kink at T2 followed by a gradual increase. This behaviour examines at various magnetic field along [001] and [100]. The B001-T and B100-T magnetic phase diagrams have been constructed. The field-induced phase appears near by the 100] magnetic field, B100.

We have studied the electrical resistivity of YbCo2Zn20 under magnetic field up to 18 T. With applying magnetic field, the contribution of the Kondo interaction to the electrical resistivity is suppressed and the Fermi liquid regime is extended to higher temperature range. Both the T2 coefficient of the electrical resistivity A and the residual resistivity ρ0 strongly decrease in magnetic field. From the magnetic variation of the resistivity, it has been found that YbCo2Zn20 is classified as a heavy fermion system with small Kondo temperature of ~ 1.0K.