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by ac calorimetryTateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo; Nakashima, Miho*; Thamizhavel, A.*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan, 75(Suppl.), p.174 - 176, 2006/08
We have investigated the physical properties of Heavy Fermion superconductors by the ac calorimetry under high pressure using a thermocouple. The method is powerful tool since the high sensitive measurement of the heat capacity is possible and the precise pressure dependence of transition temperatures such as the superconducting transition can be determined. In this conference, I would like to report our investigations on the heavy fermion superconductors CePtSi, CeNiGe and UIr. We have made pressure phase diagram of these compounds and discuss the relation between the magnetism and superconductivity.
; High-field phase diagram near an antiferromagnetic QCPTokunaga, Yo; Orlova, A.*; Bruyant, N.*; Aoki, Dai*; Mayaffre, H.*; Kr
mer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati
, M.*; Sakai, Hironori; et al.
no journal, ,
In order to understand the origin of the field-induced anomaly observed in the heavy-fermion metal CeIn at about 45 T, well before the antiferromagnetic critical field, we have performed a pulsed magnetic field In-NMR study using a single crystal up to 56 Tesla. We confirmed that there is no obvious change of hyperfine fields at In sites even above 45 T. This indicates that there is no structural change at high fields, and further, denies simple explanations of the anomaly as due to a field-induced change of the magnetic structure in CeIn.
; A Pulsed magnetic field NMR studyTokunaga, Yo
no journal, ,
CeIn exhibits a field-induced anomaly in the Fermi surface at about 45 T. In order to investigate the origin of this anomaly, a pulsed magnetic field NMR experiment has been performed using a high quality singe crystal. We confirmed that there is no obvious change in the hyperfine fields and electric field gradient at In sites through 45 T. This excludes a simple explanation of the anomaly as due to field-induced change of magnetic structure above 45 T.
Tokunaga, Yo
no journal, ,
We report pulsed-field NMR study in the prototypical heavy fermion material CeIn. The compound exhibits a field-induced anomaly in high field around 45 T. The anomaly is associated with a Fermi surface reconstruction, and has been discussed as the consequence of a Lifshitz transition or a metamagnetic transition, both of which can be driven by strong magnetic field. However, we have not detected any visible change in our pulsed-field NMR spectra that could suggest a modification either in the character of the hyperfine field or in the electric field gradient at In sites. This strongly suggests that the 45 T anomaly cannot be simply ascribed to a field-induced change of the magnetic structure in the antiferromagnetic state.