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HL: Fachverband Halbleiterphysik

HL 35: Poster I

HL 35.14: Poster

Dienstag, 8. März 2016, 15:00–19:00, Poster A

Topological phases in interfacial phase-change materials — •Peter Schmitz^1,3, Wei Zhang², Yuriy Mokrousov³, and Riccardo Mazzarello¹ — ¹Institute for Theoretical Solid State Physics, RWTH Aachen — ²CAMP Nano, Xi’an Jiaotong university, China — ³IAS-1 and JARA, Forschungszentrum Jülich

We investigate the topological, spectral and structural properties of [Sb₂Te₃]_x[GeTe]_y compounds, some of which are interfacial phase-change materials (IPCMs), as a function of strain and stacking sequence using density functional theory.
Induced by electric fields and heat, IPCMs can perform fast reversible transitions between crystalline states of different stacking. Since they possess strong SOC and a TI+NI layering, they are a promising platform for nontrivial interface states and switching between topological phases. So far they were shown to exhibit TIs and unstable TI/NI transition points [1], yet no consistent classification exists.
We analyze if the novel 3D topological Dirac semimetal (TDSM) phase [2] is relevant to these C₃ systems: Under parameter variation, 2 cones move through the bulk spectrum, gapped due to symmetry breaking potentials between the blocks which enables nonzero 3D Z₂ invariants. We show that corresponding states are localized at the interfaces of iPCMs and the effective topological phase is controlled by their van der Waals interaction.
[1] J. Tominaga et al, Adv. Mat. Inter. 1 (2014)
[2] B. Yang and N. Nagaosa, Nature Commun. 5, 4898 (2014)