Similarity of Fermi Surface in the Hidden Order State and in the Antiferromagnetic State of URu2Si2

TL;DR

This study uses Shubnikov-de Haas measurements to compare the Fermi surfaces in the hidden order and antiferromagnetic phases of URu2Si2, revealing their similarity and implications for the nature of the hidden order.

Contribution

It demonstrates that the Fermi surface in the hidden order phase is similar to that in the antiferromagnetic phase, suggesting lattice doubling occurs in both states.

Findings

Two new Fermi surface branches observed in hidden order phase

Fermi surface remains similar under pressure in antiferromagnetic state

Lattice doubling likely occurs in both phases

Abstract

Shubnikov-de Haas measurements of high quality URu2Si2 single crystals reveal two previously unobserved Fermi surface branches in the so-called hidden order phase. Therefore about 55% of the enhanced mass is now detected. Under pressure in the antiferromagnetic state, the Shubnikov-de Haas frequencies for magnetic fields applied along the crystalline c axis show little change compared with the zero pressure data. This implies a similar Fermi surface in both the hidden order and antiferromagnetic states, which strongly suggests that the lattice doubling in the antiferromagnetic phase due to the ordering vector QAF = (0 0 1) already occurs in the hidden order. These measurements provide a good test for existing or future theories of the hidden order parameter.