Title: Michal Vališka:Superconducting and normal state properties of nearly ferromagnetic UTe2 under hydrostatic pressure and high magnetic field
Number: 6/20
Status: Closing date exceeded
Begin: cancelled (Wednesday, 19.02. 2020, 14:10)
Tutor: Vladimír Sechovský
Location: lecture room F2, first floor Ke Karlovu 5

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We have a pleasure to invite you to attend the joint seminar
of the Department of Condensed Matter Physics (DCMP)
and the Materials Growth and Measurement Laboratory (MGML)




Superconducting and normal state properties of nearly ferromagnetic UTe2 under hydrostatic pressure and high magnetic field

lecture given by:

Michal Vališka

Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic

The seminar takes place in the lecture room F2 
of the Faculty of Mathematics and Physics, Ke Karlovu 5, Praha 2
on Wednesday, 19.2. 2019 from 14:10 

Vladimír Sechovský
On behalf of the DCMP and MGML


We report the effect of applied hydrostatic pressure and high magnetic field on the recently discovered superconductor UTe2. This heavy-fermion paramagnet exhibits superconductivity at Tsc = 1.6 K at ambient pressure and crystalizes in the orthorhombic Immm space group. Although UTe2 has a paramagnetic ground state its magnetic susceptibility for field parallel to a axis is strongly enhanced, suggesting its vicinity to ferromagnetic order, and indeed it shares some of the remarkable properties of the uranium based ferromagnetic superconductors (UGe2, URhGe, UCoGe, and UIr). Both URhGe and UCoGe have remarkable phase diagrams under magnetic field Hǁb perpendicular to the orientation of the magnetic moments along c axis. This causes reinforcement of superconductivity for UCoGe and reentrant superconductivity for URhGe corresponding to the reorientation of the moments and increased magnetic fluctuations. The upper critical field Hc2 of UTe2 exceeds the Pauli limit, suggesting spin-triplet coupling, and is strongly anisotropic. Hc2 for magnetic field applied along b axis shows dramatic upturn for the high quality samples that resembles the case of UCoGe and URhGe. The magnetic susceptibility for Hǁb has a maximum at Tχmax = 35 K. Thus, in further analogy with UCoGe and URhGe, a metamagnetic transition was predicted and finally confirmed by high-field experiments at µ0Hm = 35 T.

We performed transport and calorimetry measurements under hydrostatic pressure and high magnetic field in order to construct the complete p-T-H phase diagram of UTe2 that shows the evolution of both the normal and superconducting state of the system.