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We performed ultrasonic and temperature measurements under pulsed magnetic fields on CeIrIn$_5$ to investigate whether or not the origin of metamagnetic transition and field-induced Lifshitz transition was described by the anisotropic electronic ordering with crystal symmetry breaking. We observed elastic anomalies with the negative magnetocaloric effects around the field-induced Lifshitz transition and the metamagnetic transition. On the other hand, the elastic anomalies appeared both in the transverse elastic constants $(C_{11} - C_{12})/2$ and $C_{66}$ in CeIrIn$_5$ while $(C_{11} - C_{12})/2$ showed significant elastic anomaly at the crystal symmetry breaking fields in CeRhIn$_5$. These results indicate that the anisotropic electronic ordering with crystal symmetry breaking is absent in high-magnetic fields in CeIrIn$_{5}$., 6 pages, 2 figures, Accepted in JPS Conf. Proc. (LT29) (08/31/2022)

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We report the first successful observation of the de Haas–van Alphen (dHvA) effect in Eu-based filled skutterudite EuRu 4 Sb 12 which shows a ferromagnetic transition at T C =3.3 K. The dHvA frequencies and those angular dependences are highly different from those for the trivalent compounds such as LaRu 4 Sb 12 and PrRu 4 Sb 12 . This fact is consistent with the results of magnetic susceptibility and the X-ray absorption near edge spectroscopy measurements which have revealed a nearly divalent Eu electronic configuration. The cyclotron effective masses have been estimated ranging from 1.6 m 0 to 2.6 m 0 .

この論文は国立情報学研究所の電子図書館事業により電子化されました。

Conventional magnetic field sensors are searched to detect the magnetic field intensity of a superconducting magnet. Characteristics of some commercial Hall sensors are studied under a high magnetic field up to 25T at temperatures from 1.5K to 300K. A fully computerized system with a calibrated GaAs Hall sensor is applied to determine the magnetic field strength in the acoustic dHvA experiments.

We have carried out high pressure experiment on the pressure-induced superconductor CeIrSi$_3$ without inversion center. The electrical resistivity and ac heat capacity were measured in the same run for the same sample. The critical pressure of the antiferromagnetic state was determined to be $P_{\rm c}$ = 2.25 GPa. The heat capacity $C_{\rm ac}$ shows both antiferromagnetic and superconducting transitions at pressures close to $P_{\rm c}$. The superconducting transition temperature $T_{\rm sc}$ shows a maximum value of 1.6 K around $2.5-2.7$ GPa. At 2.58 GPa, a large heat capacity anomaly was observed at $T_{\rm sc}$ = 1.59 K. The jump of the heat capacity in the form of ${\Delta}{C_{\rm ac}}/C_{\rm ac}(T_{\rm sc})$ is 5.7 $\pm$ 0.1. This is the largest value observed among all superconductors studied previously, suggesting the strong-coupling superconductivity in CeIrSi$_3$. The large magnitude and anisotropy of the upper critical field $B_{\rm c2}$ at 2.65 GPa is discussed from view points of the strong-coupling superconductivity and the reduced paramagnetic effect in the non-centrosymmetric superconductor. Above $P_{\rm c}$, the electrical resistivity shows the anomalous $T$-linear dependence in the wide temperature region from $T_{\rm sc}$ to 30 K, which is different from the Fermi liquid theory. Meanwhile, the heat capacity $C_{\rm ac}/T$ shows a simple temperature dependence in the normal state above $T_{\rm sc}$. These features do not seem to be explained simply by the spin fluctuation theory. The electronic specific heat coefficient at $T_{\rm sc}$ is approximately unchanged as a function of pressure, even at $P_{\rm c}$., Comment: This paper is prepared for ``5th International Conference on Magnetic and Superconducting Materials, MSM07 (25th-30th September 2007, Khiva, Uzbekistan)"

この論文は国立情報学研究所の電子図書館事業により電子化されました。, 研究会報告

この論文は国立情報学研究所の電子図書館事業により電子化されました。, アブストラクト