Dresden 2020 – wissenschaftliches Programm

Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 2: Superconductivity: Sample Preparation, Characterization, Properties and Electronic Structure

TT 2.4: Vortrag

Montag, 16. März 2020, 10:15–10:30, HSZ 103

STM and STS studies of superconducting 1T-TaSeS — •Marion A. van Midden¹, Yaroslav Gerasimenko^1,2, Petra Šutar¹, Erik Zupanič¹, and Dragan Mihailovic^1,2 — ¹Jožef Stefan Institute, Ljubljana, Slovenia — ²Center of Excellence in Nanoscience and Nanotechnology, Ljubljana, Slovenia

In 1T-TaS₂, similarly to many high-temperature superconductors, superconductivity, charge density waves (CDW) and Mott insulating (MI) states coexist. The MI state is suppressed upon doping [1], substitution [2] or pressure [3]. Until recently, it has been believed that this, together with the formation of CDW domain walls, is crucial for the onset of superconductivity. However, recent studies at T > T_SC have challenged this hypothesis in 1T-TaS₂ and 1T-TaSe_xS_2−x [4].

We study superconducting 1T-TaSeS close to optimal T_SC = 3.5 K using high-resolution scanning tunneling spectroscopy (STS) both below and above T_SC. In contrast to pure 1T-TaS₂ we observe a finite density of states inside the Mott gap both inside the domains and at the domain walls. STS at T = 1.2 K shows a small 1-2 meV gap at the Fermi level that vanishes at T > 5K, strongly suggesting it is related to SC. It is clearly uncorrelated with the CDW domain walls of any kind in clear contrast with the simple domain wall picture. This suggest a different, correlated picture of SC onset.

[1] L. J. Li et al., European Physics Letters 97, 67005 (2012).

[2] Y. Liu et al., Applie Physics Letters. 102, 192602 (2013).

[3] B. Sipos et al., Nature Materials 7, 960 (2008).

[4] J. Skolimowski, Y. Gerasimenko and R. Žitko, PRL, 122 (2019).