AC magnetic susceptibility studies of single crystalline CeNiGe2 under high pressure

金沢大学大学院自然科学研究科環境計画The magnetic susceptibility of CeNiGe2 single crystal has been measured under high pressure up to 2.0 GPa. Although two anomalies are observed at TN1=4.0 K and at TN2=3.0 K at ambient pressure, TN2 disappears above 0.13 GPa, while TN1 still remains near 2.0 K up to 2.0 GPa. On the other hand, the peak height of the susceptibility curve decreases with increasing pressure, which may suggest that the correlation between conduction and f-electrons is strengthened by pressure. The Kondo temperature TK is estimated from the maximum of χc–T curve. TK is remarkably enhanced by applying pressure

Magnetotransport in the magnetic superconductor HoNi₂B₂C

金沢大学理工研究域環境デザイン学系The electrical resistivity and the magnetization of single crystalline HoNi2B2C have been measured at several magnetic fields. In the paramagnetic region, the magnetization is nicely reproduced by calculations that take the crystal electric field (CEF) into consideration. The magnetoresistance is negative at a wide temperature range, and is strongly dependent on the magnetization. It is interpreted by the reduction of spin-disorder scattering as the moments are polarized. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Magnetic Phase Diagram of Ce1-xErxAl2 intermetallic compounds

The magnetic and thermal properties of Ce1−xErxAl2 compounds have been studied using electrical resistivity and magnetic susceptibility measurements. The magnetic ordering temperature continuously changes with a change from antiferro-magnetism (CeAl2) to ferro-magnetism (ErAl2) appears. The magnetic ordering temperature is continuously changed as a function of Er concentration x. A spin glass behavior was found between x = 0.08 and 0.4. The magnetic phase diagram was compiled as a function of x.Embargo Period 12 month

The enhanced negative magnetoresistance of Fe/Tb multilayer at multiextreme conditions

金沢大学理工研究域環境デザイン学系Magnetoresistance (MR) in Fe/Tb magnetic multilayer is studied under multiextreme conditions, i.e., high magnetic field, low temperature, and high pressure. The negative MR is observed to be 24.6% in [Fe (12 nm) /Tb (15 nm)] 25 at 4.2 K, and MR is not saturated completely even up to 30 T. With increasing pressure, the magnitude of MR tends to be suppressed, indicating that magnetic order in the Tb layers is suppressed by applying pressure. © 2008 American Institute of Physics

The negative magnetoresistance of Fe/Tb magnetic multilayer

金沢大学理工研究域環境デザイン学系Magnetic twist driven magnetoresistance in Fe/Tb magnetic multilayer is studied. The negative MR ratio is observed to be 24.6 % on [Fe(12 nm)/Tb(15 nm)]25 at 4.2 K, which is much larger than that of Tb monolayer film, 9.9 %. Such large MR has never reported in multilayer systems including rare earth metal. Assuming that the MR of Tb can also be explained by the AMR effect, it means that the MR effects of the Tb layer is enhanced by spin polarization of the Fe layers. © 2009 IOP Publishing Ltd

Thermal and magnetic properties in Ce1-xErxAl2 intermetallic compounds

The magnetic and thermal properties of Ce1−xErxAl2 compounds have been studied using specific heat, dc magnetization, and ac susceptibility measurements. All these compounds are isomorphic with the MgCu2 Laves phase, and the lattice parameter decreases almost linearly with the increasing Er concentration x. The dc magnetic susceptibility follows the Curie–Weiss law, and the Weiss temperature continuously changes from Θ = −24 K for x = 0 to Θ = 15 K for x = 1, indicating a change from antiferro-magnetism to ferromagnetism. Θ changes from negative to positive at around x = 0.2 where where a field-induced metamagnetic transition disappears. The magnetic ordering state continuously changes with the change in x from antiferromagnetic to ferromagnetic through a spin-glass-like behavior.Embargo Period 12 month

Anomalous elastic softening of SmRu_{4}P_{12} under high pressure

The filled skutterudite compound SmRu_4P_{12} undergoes a complex evolution from a paramagnetic metal (phase I) to a probable multipolar ordering insulator (phase II) at T_{MI} = 16.5 K, then to a magnetically ordered phase (phase III) at T_{N} = 14 K. Elastic properties under hydrostatic pressures were investigated to study the nature of the ordering phases. We found that distinct elastic softening above T_{MI} is induced by pressure, giving evidence of quadrupole degeneracy of the ground state in the crystalline electric field. It also suggests that quadrupole moment may be one of the order parameters below T_{MI} under pressure. Strangely, the largest degree of softening is found in the transverse elastic constant C_{T} at around 0.5-0.6 GPa, presumably having relevancy to the competing and very different Gruneisen parameters \Omega of T_{MI} and T_{N}. Interplay between the two phase transitions is also verified by the rapid increase of T_{MI} under pressure with a considerably large \Omega of 9. Our results can be understood on the basis of the proposed octupole scenario for SmRu_4P_{12}.Comment: 7 pages, 7 figure