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Shimizu, Yusei*; Haga, Yoshinori; Yanagisawa, Tatsuya*; Amitsuka, Hiroshi*; Aoki, Dai*; Brison, J.-P.*; Braithwaite, D.*
JPS Conference Proceedings (Internet), 3, p.015009_1 - 015009_6, 2014/06
SiKambe, Shinsaku; Aoki, Dai*; Salce, B.*; Bourdarot, F.*; Braithwaite, D.*; Flouquet, J.*; Brison, J.-P.*
Physical Review B, 87(11), p.115123_1 - 115123_6, 2013/03
Times Cited Count：9 Percentile：40.37(Materials Science, Multidisciplinary)The temperature dependence of the thermal expansion coefficient 
has been measured in URuSi under uniaxial pressure 
along the [100] and [110] directions up to 
GPa. For both cases, the hidden order phase transition temperature 
increases with increasing uniaxial pressure. An anomaly 
of the thermal expansion coefficient at appears to be enhanced under a small uniaxial pressure (
GPa). An antiferromagnetically ordered phase appears at 
above the critical pressure 
GPa for uniaxial pressure along the [100] direction, whereas no antiferromagnetic transition is detected up to GPa for uniaxial pressure along the [110] direction, indicating that the critical pressure is beyond GPa for the [110] case.
Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Ueda, Taiki*; Thamizhavel, A.*; Nakashima, Miho*; Takeuchi, Tetsuya*; Settai, Rikio*; Onuki, Yoshichika; Knebel, G.*; et al.
no journal, ,
We have developed the system for the heat capacity measurement by the thermocouple in order to study the high pressure physical properties of the rare earth and actinide compounds. In this talk, we would like to show our system and discuss our recent results on the heavy fermion superconductors CePt
Si and UIr. It is noted that the superconductivity of UIr was found by our group. There is no inversion center in crystal structures of both compounds. The superconductivity of both compounds might be the novel type. In the case of CePtSi, the antiferromagnetic phase is strongly suppressed by the applied pressure and disappears above 0.6 GPa, while the superconducting phase exists in the wide pressure region up to 1.5 GPa. It is found that the overall feature of the pressure phase diagram is different from those of other heavy fermion superconductors. In the case of UIr, it is suggested by the resistivity measurement under pressures that there exists multiple ferromagnetic phases in the high pressure region. We investigated the pressure phase diagram of UIr from the thermodynamic point of view. We discuss the relation between the superconductivity and magnetism in UIr.
Matsuda, Tatsuma; Aoki, Dai*; Kotegawa, Hisashi*; Hassinger, E.*; Taufour, V.*; Knebel, G.*; Braithwaite, D.*; Salce, B.*; Yamamoto, Etsuji; Haga, Yoshinori; et al.
no journal, ,
no abstracts in English
SiKambe, Shinsaku; Aoki, Dai*; Salce, B.*; Braithwaite, D.*; Flouquet, J.*; Brison, J. P.*
no journal, ,
1 axis of the order transition temperature T0 in which URuSi hid, and the antiferromagnetic order TN. It experimented about pressure dependence. Quality single crystal 2 (a axis) 
2(c axis) 4.2(a axis) mm was used. Hidden order and antiferromagnetic order transition. In order to detect, the thermal expansion coefficient was measured using the string gauge. 1 axis pressure is Sis who can change pressure continuously at low temperature using helium gas. Tem is used and it is measurement to [100] direction (direction of 4.2 mm of a axes) 5 kbar. It carried out. Under hydrostatic pressure, although TN appeared from about 5 kbar, with the 1 axis of [100] direction pressure, it turned out that it appears from about 3 kbar. Moreover, T0 is going up. This consistents with as a result of neutron scattering. [0 01] It combines with a direction and the experimental result under hydrostatic pressure, and performs thermodynamic consideration.
Si, 2Kambe, Shinsaku; Aoki, Dai*; Salce, B.*; Bourdarot, F.*; Braithwaite, D.*; Flouquet, J.*; Brison, J. P.*
no journal, ,
It experimented about the 1 axis pressure dependence of order transition temperature T
in which URuSi hid, and antiferromagnetic order T
. 224 mm of quality single crystals were used. In order to detect the hidden order and antiferromagnetic order transition, the thermal expansion coefficient was measured using the string gauge. The 1 axis pressure sigma performed measurement to [100], the [110] directions, and 0.6 GPa using the system which can change pressure continuously at low temperature using He gas. Under hydrostatic pressure, although T appeared from about 0.5 GPa, with the 1 axis of [100] direction pressure, it turned out that it appears from about 0.25 GPa. Moreover, T is also going up. This consistents withas a result of neutron scattering. On the other hand, in the case of [110], T was not able to be observed to 0.6 GPa.
SiKambe, Shinsaku; Tokunaga, Yo; Sakai, Hironori; Aoki, Dai*; Salce, B.*; Bourdarot, F.*; Matsuda, Tatsuma*; Haga, Yoshinori; Braithwaite, D.*; Flouquet, J.*; et al.
no journal, ,
Recent two experimental investigations in URuSi will be presented. In first part, the temperature dependence of the thermal expansion coefficient will be presented in URuSi under uniaxial pressure along the [100] and [110] directions up to GPa. For both cases, the hidden order phase transition temperature increases with increasing uniaxial pressure. An antiferromagnetically ordered phase appears at above the critical pressure GPa for uniaxial pressure along the [100] direction, whereas no antiferromagnetic transition is detected up to GPa for uniaxial pressure along the [110] direction, indicating that the critical pressure is beyond GPa for the [110] case. 2-fold intrinsic (mono-domain) susceptibility anisotropy in the basal plane, a value 
times smaller than that obtained from recent susceptibility measurements.
Tokunaga, Yo; Aoki, Dai*; Braithwaite, D.*; Knebel, G.*; Brison, J.-P.*; Pourret, A.*; Lapertot, G.*; Niu, Q.*; Valiska, M.*; Flouquet, J.*; et al.
no journal, ,
In this study, using a single crystal of URhGe, we performed zero-field NMR study under uniaxial stress. For all the observed NMR peaks, a successive shift toward lower frequencies has been ob- served with increasing the uniaxial stress. The behavior indicates uniform and successive change of local environments at the nuclear positions. Simultaneously, however, we have also seen a broadening of the NMR peaks with increasing the stress, in particular above 0.8 GPa, suggesting the distribution of the local environments with larger stresses.
Tokunaga, Yo; Aoki, Dai*; Braithwaite, D.*; Knebel, G.*; Brison, J.-P.*; Pourret, A.*; Lapertot, G.*; Niu, Q.*; Valiska, M.*; Flouquet, J.*; et al.
no journal, ,
Recently, uniaxial stress has been found to be a remarkable tool for tuning the pairing strength in a ferromagnetic superconductor URhGe. A relatively small uniaxial stress applied along the 
crystal axis changes the superconducting (SC) phase diagram significantly, merging the low-field SC and reentrant SC domes, with a large enhancement of 
. The increases both at zero field and under a field, reaching 1 K, more than twice higher than at ambient pressure. This enhancement of SC has been shown to be directly related to a change of the magnetic dimensionality, moving the system away from the Ising-type limit, which results in the rapid decrease of the 
. In this study, by means of zero-field 
Ge NMR in the ferromagnetic state, we have investigated the effects of uniaxial stress on the electronic state of URhGe.
