Epitaxy, exfoliation, and strain-induced magnetism in rippled Heusler membranes

Abstract

Single-crystalline membranes of functional materials enable the tuning of properties via extreme strain states; however, conventional routes for producing membranes require the use of sacrificial layers and chemical etchants, which can both damage the membrane and limit the ability to make them ultrathin. Here we demonstrate the epitaxial growth of the cubic Heusler compound GdPtSb on graphene-terminated Al${}_2$O${}_3$ substrates. Despite the presence of the graphene interlayer, the Heusler films have epitaxial registry to the underlying sapphire, as revealed by x-ray diffraction, reflection high energy electron diffraction, and transmission electron microscopy. The weak Van der Waals interactions of graphene enable mechanical exfoliation to yield free-standing GdPtSb membranes, which form ripples when transferred to a flexible polymer handle. Whereas unstrained GdPtSb is antiferromagnetic, measurements on rippled membranes show a spontaneous magnetic moment at room temperature, with a saturation magnetization of 5.2 bohr magneton per Gd. First-principles calculations show that the coupling to homogeneous strain is too small to induce ferromagnetism, suggesting a dominant role for strain gradients. Our membranes provide a novel platform for tuning the magnetic properties of intermetallic compounds via strain (piezomagnetixm and magnetostriction) and strain gradients (flexomagnetism).

References in corpus (4)

• Role of the conduction electrons in mediating exchange interactions in Heusler alloys
• Bending strain-tunable magnetic anisotropy in Co2FeAl Heusler thin film on Kapton
• Switching a polar metal via strain gradients
• High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

Cited by in corpus (13)

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• Cold Seeded Epitaxy and Flexomagnetism in Smooth GdAuGe Membranes Exfoliated from graphene/Ge(111)
• Control of ternary alloy composition during remote epitaxy on graphene
• Thin films as practical quantum materials: a status quo and beyond
• Emergent magnetism with continuous control in the ultrahigh conductivity layered oxide PdCoO2
• Quantifying Mn diffusion through transferred versus directly-grown graphene barriers
• Freestanding Thin-Film Materials
• How transparent is graphene? A surface science perspective on remote epitaxy
• Propagation of elastic waves in a flexomagnetic solid
• Tunable polar distortions and magnetism in Gd${}_x$La${}_{1-x}$PtSb epitaxial films
• Reconfigurable Strain Gradient Polarity in Crystalline Oxide Nanomembranes for Controlled Bending of Functional Materials