Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 78: Correlated Electrons: Poster Session
TT 78.57: Poster
Donnerstag, 10. März 2016, 15:00–18:30, Poster D
Ground state properties of MnB4 — •Jan Lennart Winter1, Nico Steinki1, Dirk Schulze Grachtrup1, Dirk Menzel1, Stefan Süllow1, Arno Knappschneider2, and Barbara Albert2 — 1Institut für Physik der Kondensierten Materie, TU Braunschweig, Germany — 2Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, TU Darmstadt, Germany
Recently, single crystalline MnB4 was synthesized for the first time, yielding microscale crystals with dimensions of the order of 200 µm [1]. Based on band structure calculations, it was argued that the material is semiconducting as result of a Peierls distortion. Conversely, in a study of polycrystalline material it was concluded that the material is a weakly ferromagnetic metal [2].
To establish if MnB4 is a semiconductor we have carried out single crystal four point resistivity measurements. For this purpose a setup for measuring microscale samples was developed and characterized. Qualitatively, we find semiconducting behavior (increasing resistivity for decreasing temperature), although a band gap could not be derived because of a non-linear Arrhenius plot. Our data are consistent with MnB4 being a pseudogap/small gap material as proposed in [1]. A pronounced sample dependence of the transport properties points to the presence of impurity states. For the single crystals no ferromagnetic signatures could be obtained, suggesting an extrinsic cause of it in polycrystalline material.
A. Knappschneider et al., Angew. Chem. 126, 1710 (2014)
H. Gou et al., PRB 89, 064108 (2014)