Shota Nakamura

Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB6

Experimental study of the Kondo insulator SmB6 provides an alternative route to realize a Fermi surface in the absence of a conventional Fermi liquid.

Gap structure of FeSe determined by angle-resolved specific heat measurements in applied rotating magnetic field

Yue Sun, Shunichiro Kittaka, Shota Nakamura, Toshiro Sakakibara, Koki Irie, Takuya Nomoto, Kazushige Machida, Jingting Chen, and Tsuyoshi Tamegai Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581, Japan Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan RIKEN Center for Emergent Matter Science (CEMS), Hirosawa, Wako, Saitama 351-0198, Japan Department of Applied Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan

Quasiparticle excitations and evidence for superconducting double transitions in monocrystalline U0.97Th0.03Be13

Superconducting (SC) gap symmetry and magnetic response of cubic U0.97Th0.03Be13 are studied by means of high-precision heat-capacity and dc magnetization measurements using a single crystal, in order to address the long-standing question of its second phase transition at Tc2 in the SC state below Tc1. The absence (presence) of an anomaly at Tc2 in the field-cooling (zero-field-cooling) magnetization indicates that this transition is between two different SC states. There is a qualitative difference in the field variation of the transition temperatures; Tc2(H) is isotropic whereas Tc1(H) exhibits a weak anisotropy between [001] and [111] directions. In the low temperature phase below Tc2(H), the angle-resolved heat-capacity

Fermi Surfaces in Kondo Insulators

C(T,H, \phi)

Wing structure in the phase diagram of the Ising ferromagnet URhGe close to its tricritical point investigated by angle-resolved magnetization measurements

reveals that the gap is fully opened over the Fermi surface, narrowing down the possible gap symmetry.

Disorder-sensitive nodelike small gap in FeSe

We report magnetic quantum oscillations measured using torque magnetisation in the Kondo insulator YbB12 and discuss the potential origin of the underlying Fermi surface. Observed quantum oscillations as well as complementary quantities such as a finite linear specific heat capacity in YbB12 exhibit similarities with the Kondo insulator SmB6, yet also crucial differences. Small heavy Fermi sections are observed in YbB12 with similarities to the neighbouring heavy fermion semimetallic Fermi surface, in contrast to large light Fermi surface sections in SmB6 which are more similar to the conduction electron Fermi surface. A rich spectrum of theoretical models is suggested to explain the origin across different Kondo insulating families of a bulk Fermi surface potentially from novel itinerant quasiparticles that couple to magnetic fields, yet do not couple to weak DC electric fields.

Investigation of the tricritical point of the ising ferromagnet URhGe by angle-resolved measurements

High-precision angle-resolved dc magnetization and magnetic torque studies were performed on a single-crystalline sample of URhGe, an orthorhombic Ising ferromagnet with the

Observation of a new field-induced phase transition and its concomitant quantum critical fluctuations in CeCo(In1−xZnx)5

c

Soft-mode behavior in lanthanide-modified bismuth titanates

axis being the magnetization easy axis, in order to investigate the phase diagram around the ferromagnetic (FM) reorientation transition in a magnetic field near the

Superconductivity and Non-Fermi-Liquid Behavior in the Heavy-Fermion Compound CeCo1−xNixIn5

b