AQP -seminaari: Electronic instabilities of metallic dichalcogenides: Unconventional superconductivity and Kondo magnetism

Seminar title:

Electronic instabilities of metallic dichalcogenides: Unconventional superconductivity and Kondo magnetism

In this seminar, I will talk about how unconventional features of superconductivity and magnetism emerge when thinning down different metallic transition metal dichalcogenides to the monolayer limit. I will first show how monolayer 1H-NbSe2 displays very prominent collective mode resonances in the tunneling spectrum, which are only seen in the superconducting state. I will argue that a likely origin of these resonances is a collective mode due superconducting fluctuations to a competing f-wave triplet channel, and show a minimal theory model to support this claim. In the second part of the talk I will discuss how the 1T/1H-TaSe2 bilayer forms an effective Kondo lattice, where a Kondo peak is observed in STM which is split at very low temperatures. I will then argue that this splitting likely originates from a magnetic ground state of the Kondo lattice, and discuss quantitatively how proximate this state is to the quantum critical point in the Doniach phase diagram. I will conclude with a discussion of the implications of our results for the recently observed superconductivity in 4Hb TaS2.