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Ota, Kyugo*; Matsumoto, Yuji*; Watabe, Yuki*; Kaneko, Koji; Tabata, Chihiro; Haga, Yoshinori
New Physics; Sae Mulli, 73(12), p.1170 - 1173, 2023/12
We have performed the neutron scattering study of antiferromagnet UPt
Al
with the honeycomb lattice to determine the magnetic structure. U
Pt
Al
exhibits two phase transitions at
= 9 K and
= 26 K. In phase I at
, the magnetic reflections described by a propagation vector
= (1/3, 0, 0) were observed. In phase II at
, magnetic reflections of
= (1/3, 0, 0) and
= (1/2, 0, 0) were observed and the magnetic reflection intensity of
= (1/3, 0, 0) is weak but finite. The hysteresis in the temperature dependent intensities is observed across the phase transition at
, suggesting that the transition at
is of first order.
Tabata, Chihiro; Kon, Fusako*; Amitsuka, Hiroshi*; Shimizu, Yusei*; Aoki, Dai*; Nakao, Hironori*
no journal, ,
Sakai, Hironori; Tokiwa, Yoshifumi; Opletal, P.; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; Aoki, Dai*; Kambe, Shinsaku; Tokunaga, Yo; Haga, Yoshinori
no journal, ,
We have recently developed and optimized a molten salt flux method for growing high-purity single crystals of the superconductor UTe. The obtained crystals show a remarkably large residual resistivity ratio to the room temperature value and a small residual electronic contribution in specific heat well below
. Using the high-quality single crystal of UTe
, we have explored the superconducting phase diagram under magnetic fields along the hard magnetic
-axis. Simultaneous electrical resistivity and AC magnetic susceptibility measurements discern low- and high-field SC (LFSC and HFSC, respectively) phases with contrasting field-angular dependence. Crystal quality increases the upper critical field of the LFSC phase, but the characteristic field of
15 T, at which the HFSC phase appears, is always the same through the various crystals. A phase boundary signature is also observed inside the LFSC phase near the characteristic field of 15 T, indicating an intermediate SC phase characterized by small flux pinning forces.
Haga, Yoshinori; Yamamoto, Etsuji; Nakamura, Ai*; Honda, Fuminori*; Aoki, Dai*; Matsumoto, Yuji*; Yamamura, Tomoo*; Shirasaki, Kenji*; Yamagami, Hiroshi*
no journal, ,
Kaneko, Koji; Stockert, O.*; Tabata, Chihiro; Kuwahara, Keitaro*; Kiyanagi, Ryoji; Nakao, Akiko*; Krellner, C.*; Geibel, C.*
no journal, ,
Tokiwa, Yoshifumi; Opletal, P.; Sakai, Hironori; Yamamoto, Etsuji; Kambe, Shinsaku; Tokunaga, Yo; Haga, Yoshinori; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; et al.
no journal, ,
We study the interplay between superconductivity and metamagnetism of Ute under magnetic field along the easy a-axis by analyzing the entropy, obtained from measurements of magnetization and magnetocaloric effect. Due to the weak metamagnetism around 8T the entropy in the normal-conducting state at high temperautres above the superconducting transition temperature, Tc, exhibits an anomalous enhancement as a function of the field at the metamagnetism. Suprisingly the anomaly persists even inside the superconducting state and transforms into a sharp anomaly. The anomaly is a step-wise increase of entropy with increasing magnetic field, corresponding to a heat absorbtion. Thus, we found an unprecedented phenomenon of a metamagnetism inducing a first-order phase transition within a superconducting state. We discuss that a transition within the same symmetry of
with a step-wise increase of
weight would be consistent with our observations.
Opletal, P.; Sakai, Hironori; Haga, Yoshinori; Miyake, Atsushi*; Tokunaga, Masashi*; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Kambe, Shinsaku; Tokunaga, Yo
no journal, ,
Kitazawa, Takafumi; Tokunaga, Yo; Haga, Yoshinori; Opletal, P.; Sakai, Hironori; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Kambe, Shinsaku; Ikeda, Yoichi*; Fujita, Masaki*
no journal, ,