On Sharp Enhancement of Effective Mass of Quasiparticles and Coefficient of T2 Term of Resistivity around First-Order Metamagnetic Transition Observed in UTe2

The mechanism underlying the enhancement of the Sommerfeld coefficient of quasiparticles at the first-order metamagnetic transition in UTe2, reported by Miyake et al. in J. Phys. Soc. Jpn. 88, 063706 (2019), is discussed theoretically by taking into account the ferromagnetic order-parameter fluctuations on the basis of the Landau theory of phase transition. We find that the enhanced ferromagnetic spin fluctuation gives rise to the enhancement of the effective mass of the quasiparticles or the Sommerfeld coefficient gamma, which is consistent with the experimental observations. At the same time, the Kadowaki-Woods type scaling around the metamagnetic transition, reported by Imajo et al. in J. Phys. Soc. Jpn. 88, 083705 (2019) and Knafo et al. in J. Phys. Soc. Jpn. 88, 063705 (2019), is also understood semiquantitatively by assuming reasonable values of parameters of Landau-type free energy reproducing key quantities characterizing the metamagnetic transition.

Automated summary

This study explores the mechanism of enhanced Sommerfeld coefficient of quasiparticles during the first-order metamagnetic transition in UTe2, attributing it to the increased ferromagnetic spin fluctuation leading to the effective mass enhancement. Additionally, the Kadowaki-Woods type scaling around the metamagnetic transition is semiquantitatively understood by assuming reasonable values of parameters in the Landau-type free energy.