Magnetic surface reconstruction in the van-der-Waals antiferromagnet Fe${}_{1+x}$Te

Abstract

Fe${}_{1+x}$Te is a two dimensional van der Waals antiferromagnet that becomes superconducting on anion substitution on the Te site. The parent phase of Fe${}_{1+x}$Te is sensitive to the amount of interstitial iron situated between the iron-tellurium layers displaying collinear magnetic order coexisting with low temperature metallic resistivity for small concentrations of interstitial iron $x$ and helical magnetic order for large values of $x$. While this phase diagram has been established through scattering [see for example E. E. Rodriguez $\text{et al.}$ Phys. Rev. B $84$, 064403 (2011) and S. Rössler $\text{et al.}$ Phys. Rev. B $84$, 174506 (2011)], recent scanning tunnelling microscopy measurements [C. Trainer $\text{et al.}$ Sci. Adv. $5$, eaav3478 (2019)] have observed a different magnetic structure for small interstitial iron concentrations $x$ with a significant canting of the magnetic moments along the crystallographic $c$ axis of $\theta$=28 $\pm$ 3${}^{\circ }$. In this paper, we revisit the magnetic structure of Fe${}_{1.09}$Te using spherical neutron polarimetry and scanning tunnelling microscopy to search for this canting in the bulk phase and compare surface and bulk magnetism. The results show that the bulk magnetic structure of Fe${}_{1.09}$Te is consistent with collinear in-plane order ($\theta =0$ with an error of $\sim$ 5${}^{\circ }$). Comparison with scanning tunnelling microscopy on a series of Fe${}_{1+x}$Te samples reveals that the surface exhibits a magnetic surface reconstruction with a canting angle of the spins of $\theta =29.8^{\circ }$. We suggest that this is a consequence of structural relaxation of the surface layer resulting in an out-of-plane magnetocrystalline anisotropy. The magnetism in Fe${}_{1+x}$Te displays different properties at the surface when the symmetry constraints of the bulk are removed.

11 pages, 6 figures, to be Published in Phys. Rev. B

References in corpus (25)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• The electronic properties of graphene
• High-temperature superconductivity in iron-based materials
• To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report
• Strong Correlations and Magnetic Frustration in the High Tc Iron Pnictides
• Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• First-order magnetic and structural phase transitions in Fe${}_{1+y}$Se${}_x$Te${}_{1-x}$
• Magnetism and its microscopic origin in iron-based high-temperature superconductors
• Bulk Superconductivity at 14 K in Single Crystals of Fe1+yTexSe1-x
• Magnetism in Fe-based superconductors
• Superconductivity in S-substituted FeTe
• Spin waves in the $(\pi ,0)$ magnetically ordered iron chalcogenide Fe${}_{1.05}$Te
• Control of tetrahedral coordination and superconductivity in FeSe0.5Te0.5 thin films
• Short-range incommensurate magnetic order near the superconducting phase boundary in Fe(1+d)Te(1-x)Se(x)
• Interstitial Iron Controlled Superconductivity in Fe1+xTe0.7Se0.3
• First-order structural transition in the magnetically ordered phase of Fe1.13Te
• Disappearance of static magnetic order and evolution of spin fluctuations in Fe${}_{1+\delta }$Se${}_x$Te${}_{1-x}$
• Influence of interstitial Fe to the phase diagram of Fe${}_{1+y}$Te${}_{1-x}$Se${}_x$ single crystals
• Magnetic excitations of Fe_{1+y}Se_xTe_{1-x} in magnetic and superconductive phases
• Disorder-driven electronic localization and phase separation in superconducting Fe1+yTe0.5Se0.5 single crystals
• Soft striped magnetic fluctuations competing with superconductivity in Fe_{1+x}Te
• Preparation of magnetic tips for spin-polarized STM on Fe_{1+y}Te
• Magnetic order tuned by Cu substitution in Fe1.1-zCuzTe
• Imitation of spin density wave order in Cu${}_3$Nb${}_2$O${}_8$

Cited by in corpus (3)

• Relating spin-polarized STM imaging and inelastic neutron scattering in the van-der-Waals ferromagnet Fe3GeTe2
• Magnetic skin effect in Pb(Fe${}_{1/2}$Nb${}_{1/2}$)O${}_3$
• Acoustic lattice instabilities at the magneto-structural transition in Fe${}_{1.057(7)}$Te