Collapse of the magnetic moment under pressure of AFe$_2$ (A = Y, Zr, Lu and Hf) in the cubic Laves phase

TL;DR

This study uses advanced electronic structure calculations to show that the magnetic moments in certain AFe2 compounds collapse under pressure, revealing universal behavior and potential quantum phase transitions.

Contribution

The paper demonstrates the pressure-induced collapse of magnetic moments in AFe2 compounds and links electronic structure features to magnetic behavior, highlighting quantum phase transition possibilities.

Findings

Magnetic moments collapse under hydrostatic pressure in all studied compounds.

Electronic origin of collapse is due to peaks near the Fermi level.

Different order quantum phase transitions are predicted for different compounds.

Abstract

The electronic structures of four Laves phase iron compounds (e.g. YFe$_2$, ZrFe$_2$, LuFe$_2$ and HfFe$_2$) have been calculated by the state-of-the-art full potential electronic structure code. The magnetic moments collapse under hydrostatic pressure. This feature is found to be universal in these materials. Its electronic origin is provided by the sharp peaks in the density of states near the Fermi level. It is shown that a first order quantum phase transition can be expected under pressure in Y(Zr, or Lu)Fe$_2$, while a second order one in HfFe$_2$. The bonding characteristics are discussed to elucidate the equilibrium lattice constant variation. The large spontaneous volume magnetostriction gives one of the most important character of these compounds. Invar anomalies in these compounds can be partly explained by the current work when the fast continuous magnetic moment decrease at the decrease of the lattice constant was properly considered. This work may remind the experimentalists of these "old" compounds and exploration of the quantum properties under high pressures are greatly encouraged.