Field-angle dependence of magnetoresistance in UTe2

Abstract

We theoretically study angle-resolved magnetoresistance under rotated magnetic field in the normal state of a spin-triplet superconductor UTe$_2$. The Wannier model derived from a GGA+$U$ calculation shows quasi-two-dimensional Fermi surfaces with warping in the $k_z$ direction, consistent with quantum oscillation measurements in the high magnetic field regime. Solving the semiclassical Boltzmann equation, we show that the Fermi surface geometry gives rise to oscillations in the magnetoresistance when the field is tilted from the $c$ axis toward the $a$ or $b$ axis. By assuming a band-dependent relaxation time, the calculated angle-resolved magnetoresistance is in good agreement with the recent transport experiment. This is direct evidence for the warped Fermi surface revealed by ordinary intraband transport. It suggests that the hole band with long relaxation time dominates electron transport. The field angle dependence of the Hall resistivity is calculated for further experimental verification.

Figures (9)

• Figure 1: (a) Crystal structure of UTe$_2$. (b) Band structure of the DFT+$U$ calculation for $U=2.0$ eV (solid lines) and the 12-band Wannier model (dashed lines) along the high symmetry lines. (c) Left: Fermi surfaces of the 12-band Wannier model. Right: 2D cut on the $k_z =0$ plane. The magnitude of Fermi velocity is indicated by color.
• Figure 2: (a)-(c) Magnetic field $B$ dependence of diagonal resistivity, namely, the magnetoresistance, for the field angle $\theta=\phi=0$ deg. The temperature is varied from $30$ K to $330$ K. (d)-(f) Field angle $\theta$ dependence of resistivity at various angles $\phi$ for $B=8.08$ T and $T=90$ K. A band-independent relaxation time $\tau_{\rm h}=\tau_{\rm e}=1.0$ ps is assumed.
• Figure 3: Field angle $\theta$ dependence of band-resolved resistivity [(a), (b)] and conductivity [(c), (d)]. We set the same parameters as Fig. \ref{['fig:rho-diag_tau1.0']}(f), $B=8.08$ T, $T=90$ K, and $\tau_{\rm h}=\tau_{\rm e}=1.0$ ps, and illustrate the results for each field angle $\phi$ by the same color. Dashed lines in (c) and (d) depict the angles $\theta$ adopted in Figs. \ref{['fig:CrossSection']}(b) and \ref{['fig:CrossSection']}(d), respectively.
• Figure 4: (a), (b) Cross sections of the hole FS in the $k_x$-$k_z$ plane at $k_y=0$. Typical orbits of the hole carriers in the magnetic field oriented along the angle (a) $\theta=\phi=0$ deg and (b) $\theta=25$ deg and $\phi=0$ deg are labeled by (i)-(iv). (c), (d) Cross sections of the electron FS in the $k_y$-$k_z$ plane at $k_x=0$. Orbits of the electron carriers are illustrated by dashed lines.
• Figure 5: (a)-(d) Field angle $\theta$ dependence of the $c$-axis resistivity with the band-dependent relaxation time. We fix $\tau_{\rm h}=1.0$ ps and vary $\tau_{\rm e}$ from (a) 1.0 ps to (d) 0.1 ps. The other parameters, $B=8.08$ T and $T=90$ K, are the same as Fig. \ref{['fig:rho-diag_tau1.0']}(f).