Critical slowing-down and field-dependent paramagnetic fluctuations in the skyrmion host EuPtSi; SR and NMR studies

Higa, Nonoka*; Ito, Takashi; Yogi, Mamoru*; Hattori, Taisuke; Sakai, Hironori; Kambe, Shinsaku; Guguchia, Z.*; Higemoto, Wataru; Nakashima, Miho*; Homma, Yoshiya*; et al.

Physical Review B, 104(4), p.045145_1 - 045145_7, 2021/07

https://doi.org/10.1103/PhysRevB.104.045145

High-field phase diagram of the heavy-fermion metal CeIn; Pulsed-field NMR study on single crystals up to 56 T

Tokunaga, Yo; Orlova, A.*; Bruyant, N.*; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Higa, Nonoka; et al.

Physical Review B, 99(8), p.085142_1 - 085142_5, 2019/02

https://doi.org/10.1103/PhysRevB.99.085142

The heavy-fermion antiferromagnet CeIn exhibits a field-induced anomaly associated with Fermi surface reconstruction at 45 T, well below the antiferromagnetic (AFM) critical field that exceeds 60 T. In order to explore the origin of this anomaly, we have measured In NMR spectra in pulsed magnetic fields up to 56 T using high-quality single crystals. To within experimental resolution, we do not detect any change in the NMR spectra that could suggest a modification in either the character of the hyperfine field or the electric field gradient at In sites through . This strongly suggests that the 45 T anomaly cannot be simply ascribed to a field-induced change in the magnetic structure of the AFM state.

NMR study of CePtIn

Kambe, Shinsaku; Tokunaga, Yo; Sakai, Hironori; Hattori, Taisuke; Higa, Nonoka; Uhlirova, K.*; Custers, J.*

no journal, , 

In-NQR measurements of CePtIn were made. We succeeded in identifying at least two of the four In sites. Temperature dependent measurement of the spin lattice relaxation time was carried out. In the superconducting state. There was a strong temperature dependence of the spin lattice relaxation time. Discuss superconducting symmetry.

S-NMR study in -US

Sakai, Hironori; Hattori, Taisuke; Higa, Nonoka; Tokunaga, Yo; Tateiwa, Naoyuki; Yamamoto, Etsuji; Haga, Yoshinori; Kambe, Shinsaku; Reyes, A. P.*; Bauer, E. D.*; et al.

no journal, , 

-US is a paramagnetic narrow-gap semiconductor with the energy band gap of 90 K. A characteristic feature of -US is the strong response of the electrical resistivity to magnetic field. On the other hand, ferromagnetism is easily induced by pressure of about 1 GPa. Consequently, it is considered to be close to a ferromagnetic instability. To elucidate microscopically this very sensitive electronic states to external fields, S-NMR study has been performed. We will show our recent S-NMR results and discuss the electronic states.

S-NMR study for a narrow-gap semiconductor -US

Sakai, Hironori; Higa, Nonoka; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Tateiwa, Naoyuki; Haga, Yoshinori; Rossa, P. F. S.*; Thompson, J. D.*; Ronning, F.*; et al.

no journal, , 

-US is known as a narrow-gap semiconductor. The magnetoresistance in this compound is extremely large but anisotropic. To obtain microscopic view of the magnetism, we have carried on S-NMR study. We will discuss the magnetic properties in this system to show the recent NMR results.

Magnetic fluctuations in strongly correlated electrons system URuSi under high fields

Sakai, Hironori; Higa, Nonoka; Hattori, Taisuke; Tokunaga, Yo; Haga, Yoshinori; Kambe, Shinsaku; Goto, Takayuki*; Hirata, Michihiro*; Awaji, Satoshi*; Sasaki, Takahiko*

no journal, , 

We have performed Si nuclear magnetic resonance (NMR) experiments using single crystal of strongly correlated electrons system URuSi under high external field of about 24 T. The temperature dependence of NMR shift in the paramagnetic state varies with external fields. The temperature and field dependences of NMR shifts resembles those of magnetic susceptibility.

Sn-NMR study of successive phase transition in URhSn

Tokunaga, Yo; Shimizu, Yusei*; Maurya, A.*; Honda, Fuminori*; Nakamura, Ai*; Sato, Yoshiki*; Li, D.*; Homma, Yoshiya*; Aoki, Dai*; Higa, Nonoka; et al.

no journal, , 

Uranium-based compound URhS exhibits two successive phase transitions at 54 K and 18 K. The origin of the phase transition at 18 K has been known to be ferromagnetic ordering, while the origin of the transition at 54 K is still unknown. In this study, we have investigated the mechanism of the successive phase transitions in URhSn by using Sn-NMR.

NMR study of magnetic spin fluctuations in UTe

Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; Higa, Nonoka*; Nakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Nakamura, Ai*; Shimizu, Yusei*; et al.

no journal, , 

Recently, Ran et al. reported evidence for superconductivity in the uranium-based heavy fermion material UTe, exhibiting the rather high transition temperature of 1.6 K. The ground state of UTe is paramagnetic, not ferromagnetic. However, the compound still exhibits a very large and anisotropic upper critical field H, exceeding the Pauli limit along the three principal axes, similar to the ferromagnetic superconductors, UCoGe and URhGe. Field-induced metamagnetic transition and re-entrant superconducting behaviour have been reported under strong magnetic fields around 35 T, when a magnetic field was applied along the orthorhombic hard-magnetization b-axis. In this study, we have performed Te-NMR measurements on a newly discovered heavy fermion superconductor UTe. Our NMR data confirm a moderate Ising anisotropy for both the static (K) and dynamical susceptibilities (1/) in the paramagnetic state above about 20 K.