Coexistence of resistance oscillations and the anomalous metal phase in a lithium intercalated TiSe2 superconductor

Abstract

Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs). Their interplay may give rise to exotic quantum phenomena. Here, we show that superconducting arrays can spontaneously form in TiSe2–a TMD with coexisting superconductivity and CDW—after lithium ion intercalation. We induce a superconducting dome in the phase diagram of LixTiSe2 by using the ionic solid-state gating technique. Around optimal doping, we observe magnetoresistance oscillations, indicating the emergence of periodically arranged domains. In the same temperature, magnetic field and carrier density regime where the resistance oscillations occur, we observe signatures for the anomalous metal—a state with a resistance plateau across a wide temperature range below the superconducting transition. Our study not only sheds further insight into the mechanism for the periodic electronic structure, but also reveals the interplay between the anomalous metal and superconducting fluctuations.

Little-Parks like oscillations in lightly doped cuprate superconductors

“…We now consider the relation between our results and the Little-Parks oscillations. Our results are reminiscent to the intriguing phenomenon recently observed in ionic liquid gated TiSe2 [11] and lithium intercalated TiSe2 [12], but at temperature and magnetic field that are both over one order of magnitude higher. In TiSe2, it was proposed that a periodic structure emerged: CCDW patches with ICDW stripes at the domain boundaries.…”

“…By contrast, P-50 here emerges only in the extremely underdoped regime 𝑝 ≤ 0.08. Despite the sharp differences, there could be an intimate link between P-50 and CO, in a similar fashion to those periodic structures observed in TaS2 [33] and speculated to exist in TiSe2 [11,12]. In these transition metal dichalcogenides, CCDW and ICDW phases are identified in the phase diagram as a function of doping or pressure.…”

“…In most cases, the material under investigation needs to be nanopatterned into a ring or a periodic network [6][7][8][9]. Observing this type of oscillations in superconductors without artificial patterning often suggests highly nontrivial quantum physics at play, such as the presence of chiral edge state in MoTe2 [10] or a spontaneously emerged periodic order in TiSe2 [11,12]. The latter phenomenon was attributed to the periodic domains of commensurate charge density wave (CCDW) separated by incommensurate charge density wave (ICDW).…”

Coexisting superconductivity and charge-density wave in hydrogen-doped titanium diselenide via ionic liquid gating-induced protonation

“…1e) shows that the H loading does not alter the 1T lattice structure of the pristine material, and simply expands the unit cell by up to ∼ 0.9%. Interestingly, the lattice expansion is comparable to that driven by incorporation of Cu atoms in SC Cu x TiSe 2 (∼ 0.6%) [25] and much smaller than the one reported upon lithiation in SC Li x TiSe 2 (∼ 12%) [32]. The pronounced broadening of the XRD peaks however indicates that the protonation introduces a large degree of structural disorder in the samples, which may be partially responsible for the reentrant behaviour of ρ(300 K) upon gating times in excess of those associated to the local minimum shown in Fig.…”

“…CDW order with increasing gating time t can be more accurately tracked by considering its onset temperature, T CDW , and the intensity of the CDW peak, I CDW . The former can be identified with the position of the inflection point in the ρ(T ) curves [29,32,41], that corresponds to the minimum in dρ/d T . As shown in Fig.…”