Phase diagram of infinite layer praseodymium nickelate Pr1−xSrxNiO2 thin films

Abstract

We report the phase diagram of infinite layer Pr 1-x Sr x NiO 2 thin films synthesized via topotactic reduction from the perovskite precursor phase using CaH 2 . Based on the electrical transport properties, we find a doping-dependent superconducting dome extending between x = 0.12 and 0.28, with a maximum superconducting transition temperature T c of 14 K at x = 0.18, bounded by weakly insulating behavior on both sides. In contrast to the narrower dome observed in Nd 1-x Sr x NiO 2 , a local T c suppression near x = 0.2 was not observed for the Pr 1-x Sr x NiO 2 system. Normal state Hall effect measurements indicate mixed carrier contributions of both electrons and holes, and show a sign change in the Hall coefficient as functions of temperature and x, quite similar to that in Nd 1-x Sr x NiO 2 . Also similar is the observation of a minimum in the normal state resistivity associated with the superconducting compositions. These findings indicate an infinite layer nickelate phase diagram that is relatively insensitive to the rare-earth element, but suggest that disorder arising from the variations of the ionic radii on the rare-earth site affects the superconducting dome. High-T c cuprates are unusual materials systems, marked by a rather complex phase diagram enriched with intertwined electronic orders [1,2]. Despite exhibiting a generic doping-dependent phase diagram with common features, which many consider a hallmark of the physics of the CuO 2 planes [1], cuprates of various crystal structures [3-7] show rather diverse properties, manifested by different configurations of Cu-O stacking layers [8-10], a remarkably wide range of transition

Pressure-induced monotonic enhancement of Tc to over 30 K in the superconducting Pr0.82Sr0.18NiO2 thin films

“…In addition, the doping-dependent generalized superconducting dome was found to shift upon changing the rare-earth cations. However, a local T c valley structure of the superconducting phase was not observed in the Pr 1−x Sr x NiO 2 [43], which is strictly different from the situation in Nd 1−x Sr x NiO 2 and La 1−x (Ca/Sr) x NiO 2 [16,17,41,42]. These comparisons highlight the important role of the rare-earth cations in addition to the lattice strain applied by the SrTiO 3 substrate in determining the superconducting state of the nickelates.…”

“…In addition to Nd 1−x Sr x NiO 2 thin lms, superconductivity has also been achieved in other doped rare-earth nickelates, such as La 1−x (Ca/Sr) x NiO 2 [41,42] and Pr 1−x Sr x NiO 2 [43]. The phase diagrams of (La/Pr/Nd) 1−x Sr x NiO 2 and La 1−x Ca x NiO 2 thin lms are all featured by the superconducting phase adjacent to the weakly insulating state in the underdoped and overdoped regimes [16,17,[41][42][43]. In addition, the doping-dependent generalized superconducting dome was found to shift upon changing the rare-earth cations.…”

“…Although much recent effort has been devoted to the in nite-layer nickelates, the reported highest T c onset remains lower than 15 K [14,16,17,[41][42][43][44][45]; it thus becomes an important issue to further enhance the T c of the superconducting nickelates to higher temperatures. In this regard, the application of high pressure that has been widely employed to raise T c of cuprates [3] and iron-pnictides unconventional superconductors [46][47][48][49] should be a primary choice.…”

Observation of perfect diamagnetism and interfacial effect on the electronic structures in infinite layer Nd0.8Sr0.2NiO2 superconductors

“…Thus far, however, material synthesis remains challenging. The demonstration of perfect diamagnetism is still missing, and understanding of the role of the interface and bulk to the superconducting properties is still lacking [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . Here, we synthesized high- The search for the nickelate superconductivity was enthused by the idea of mimicking the 3 2 − 2 orbital of the single-band high-Tc cuprates 1 .…”

“…However, the recent results indicate the complex multiband structures in doped infinite-layer nickelates, suggesting a new family of superconductivity 1,2 . Numerous theoretical works have been conducted based on the bulk pictures 2 ; however, the superconductivity has only been observed in epitaxial Nd1-xSrxNiO2 and Pr1-xSrxNiO2 ultrathin films (up to ~10 nm) with an infinite-layer structure 1,[3][4][5][6][7][8][9] . In contrast, infinite-layer nickelates prepared in bulk form show only insulating behavior [10][11][12] .…”