Intrinsic magnetic properties of hexagonal LuFeO3 and the effects of nonstoichiometry

Jarrett A Moyer,Charles M Brooks,Darrell G Schlom,David A Muller,John T Heron,Rajiv Misra,Julia A Mundy,Peter Schiffer

doi:10.1063/1.4861795

Abstract

We used oxide molecular-beam epitaxy in a composition-spread geometry to deposit hexagonal LuFeO3 (h-LuFeO3) thin films with a monotonic variation in the Lu/Fe cation ratio, creating a mosaic of samples that ranged from iron rich to lutetium rich. We characterized the effects of composition variation with x-ray diffraction, atomic force microscopy, scanning transmission electron microscopy, and superconducting quantum interference device magnetometry. After identifying growth conditions leading to stoichiometric film growth, an additional sample was grown with a rotating sample stage. From this stoichiometric sample, we determined stoichiometric h-LuFeO3 to have a TN = 147 K and Ms = 0.018 μB/Fe.

Highlights

A material with coupling between the ferroelectric and ferromagnetic order parameters, called magnetoelectric coupling, could enable significant advancements of electric field controlled magnetic memories,[3,4] magnetic field sensors,[5,6] and tunable microwave filters.[7,8] Single phase materials that are simultaneously ferroelectric and ferromagnetic are, exceedingly rare due to the competing mechanisms that often drive ferroelectricity (d0 insulators) and ferromagnetism.[9]
Popular transition-metal oxide multiferroics include BiFeO310,11 and the hexagonal rare-earth manganites, exemplified by YMnO3.12–14 In addition to commonly possessing antiferromagnetic order, multiferroics are typically relegated to low temperatures,[1,9] as in YMnO3 with a Neel temperature (TN) of 70 K, or are predicted to be unable to reverse a canted magnetization with a change in polarization, as in BiFeO3,15,16 both of which are conditions that are undesirable for technological applications
It was recently reported that h-LuFeO3 is antiferromagnetically ordered at room temperature with a canted antiferromagnetic ordering at TN = 130 K,23 making it one of the few known room-temperature multiferroics.[10,11,23,26,27]

Summary

Introduction

A material with coupling between the ferroelectric and ferromagnetic order parameters, called magnetoelectric coupling, could enable significant advancements of electric field controlled magnetic memories,[3,4] magnetic field sensors,[5,6] and tunable microwave filters.[7,8] Single phase materials that are simultaneously ferroelectric and ferromagnetic are, exceedingly rare due to the competing mechanisms that often drive ferroelectricity (d0 insulators) and ferromagnetism (nond[0] conductors).[9]. We determine the intrinsic magnetic properties of h-LuFeO3 by first growing a set of samples in a compositional-spread geometry that have a range of ∼ ±10% variations in cation stoichiometry.

Results

Conclusion