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TT: Fachverband Tiefe Temperaturen

TT 54: Fe-based Superconductors

TT 54.14: Vortrag

Donnerstag, 19. März 2020, 13:00–13:15, HSZ 201

Scanning tunneling microscopy and spectroscopy on Fe_1+yTe (y=0.11, 0.12) — •Sahana Roessler, Cevriye Koz, Ulrich Schwarz, and Steffen Wirth — Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany

The antiferromagnetic compound Fe_1+yTe with tetragonal structure at room temperature displays a complex phase diagram with several structural and magnetic phase transitions within the homogeneity range 0.06 ≤ y ≤ 0.15 [1]. While Fe_1.11Te undergoes a single-phase transition from a paramagnetic tetragonal to an antiferromagnetic monoclinic phase, Fe_1.12Te exhibits a two-phase mixture of orthorhombic and monoclinic phases at temperatures below about 46 K. We compare the low-temperature microstructure [2] of these two compositions using scanning tunneling microscopy. The tunneling spectra on Fe_1.11Te displayed a shoulder at a bias voltage of 7 mV, likely related to the energy scale of the antiferromagnetic spin-density-wave order. In contrast, in Fe_1.12Te, we occasionally observed a zero-bias conductance peak in the tunneling spectra, induced by magnetic impurity scattering originating from the segregated excess interstitial Fe on the surface.

[1] C. Koz et al., Phys. Rev. B, 88, 094509 (2013)

[2] S. Rößler et al., Proc. Natl. Acad. Sci. 116, 16697 (2019).