Theory of Unconventional Spin Density Wave: A Possible Mechanism of the Micromagnetism in U-based Heavy Fermion Compounds

TL;DR

This paper introduces a novel unconventional spin density wave (SDW) model to explain micromagnetism in U-based heavy fermion compounds, supported by theoretical analysis and comparison with experimental data.

Contribution

It proposes a new SDW state with sign-changing electron-hole pair amplitude as a mechanism for micromagnetism, using an extended Hubbard model and mean field theory.

Findings

The proposed SDW explains the micromagnetism in URu2Si2.

The model reproduces key experimental properties.

It suggests a link between unconventional SDW and heavy fermion antiferromagnetism.

Abstract

We propose a novel spin density wave (SDW) state as a possible mechanism of the anomalous antiferromagnetism, so-called the micromagnetism, in URu_2Si_2 below 17.5[K]. In this new SDW, the electron-hole pair amplitude changes its sign in the momentum space as in the case of the unconventional superconductivity. It is shown that this state can be realized in an extended Hubbard model within the mean field theory. We also examine some characteristic properties of this SDW to compare with the experimental results. All these properties well explain the unsolved problem of the micromagnetism.