Ferromagnetism and giant magnetoresistance in zinc-blende FeAs monolayers embedded in semiconductor structures

TL;DR

This study demonstrates ferromagnetism and giant, tunable magnetoresistance in quasi-2D FeAs/InAs superlattices, revealing potential for spintronic devices with properties influenced by layer thickness and atomic disorder.

Contribution

It introduces a new class of FeAs/InAs superlattices exhibiting ferromagnetism and giant magnetoresistance, with insights into atomic disorder effects from first-principles calculations.

Findings

Curie temperature increases as InAs layer thickness decreases (~ t_InAs^-3)

Giant magnetoresistance up to 500% tunable by gate voltage

Atomic disorder of Fe atoms influences ferromagnetic properties

Abstract

Material structures containing tetrahedral FeAs bonds, depending on their density and geometrical distribution, can host several competing quantum ground states ranging from superconductivity to ferromagnetism. Here we examine structures of quasi two-dimensional (2D) layers of tetrahedral Fe-As bonds embedded with a regular interval in a semiconductor InAs matrix, which resembles the crystal structure of Fe-based superconductors. Contrary to the case of Fe-based pnictides, these FeAs/InAs superlattices (SLs) exhibit ferromagnetism, whose Curie temperature (Tc) increases rapidly with decreasing the InAs interval thickness t_InAs (Tc ~ t_InAs^-3), and an extremely large magnetoresistance up to 500% that is tunable by a gate voltage. Our first principles calculations reveal the important role of disordered positions of Fe atoms in the establishment of ferromagnetism in these quasi-2D FeAs-based SLs. These unique features mark the FeAs/InAs SLs as promising structures for spintronic applications.