Carrier density crossover and quasiparticle mass enhancement in a doped 5$d$ Mott insulator

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Hauptverfasser: Hsu, Yu-Te, Rydh, Andreas, Berben, Maarten, Duffy, Caitlin, de la Torre, Alberto, Perry, Robin S, Hussey, Nigel E
Format: Preprint
Veröffentlicht: 2023
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author Hsu, Yu-Te
Rydh, Andreas
Berben, Maarten
Duffy, Caitlin
de la Torre, Alberto
Perry, Robin S
Hussey, Nigel E
author_facet Hsu, Yu-Te
Rydh, Andreas
Berben, Maarten
Duffy, Caitlin
de la Torre, Alberto
Perry, Robin S
Hussey, Nigel E
contents High-temperature superconductivity in cuprates emerges upon doping the parent Mott insulator. Robust signatures of the low-doped electronic state include a Hall carrier density that initially tracks the number of doped holes and the emergence of an anisotropic pseudogap; the latter characterised by disconnected Fermi arcs, closure at a critical doping level $p^* \approx 0.19$, and, in some cases, a strongly enhanced carrier effective mass. In Sr$_2$IrO$_4$, a spin-orbit-coupled Mott insulator often regarded as a 5$d$ analogue of the cuprates, surface probes have revealed the emergence of an anisotropic pseudogap and Fermi arcs under electron doping, though neither the corresponding $p^*$ nor bulk signatures of pseudogap closing have as yet been observed. Here, we report electrical transport and specific heat measurements on Sr$_{2-x}$La$_x$IrO$_4$ over an extended doping range 0 $\leq x \leq$ 0.20. The effective carrier density $n_{\rm H}$ at low temperatures exhibits a crossover from $n_{\rm H} \approx x$ to $n_{\rm H} \approx 1+x$ near $x$ = 0.16, accompanied by \textcolor{blue}{a five-orders-of-magnitude increase in conductivity} and a six-fold enhancement in the electronic specific heat. These striking parallels in the bulk pseudogap phenomenology, coupled with the absence of superconductivity in electron-doped Sr$_2$IrO$_4$, disfavour the pseudogap as a state of precursor pairing and thereby narrow the search for the key ingredient underpinning the formation of the superconducting condensate in doped Mott insulators.
format Preprint
id arxiv_https___arxiv_org_abs_2312_00515
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Carrier density crossover and quasiparticle mass enhancement in a doped 5$d$ Mott insulator
Hsu, Yu-Te
Rydh, Andreas
Berben, Maarten
Duffy, Caitlin
de la Torre, Alberto
Perry, Robin S
Hussey, Nigel E
Strongly Correlated Electrons
Superconductivity
High-temperature superconductivity in cuprates emerges upon doping the parent Mott insulator. Robust signatures of the low-doped electronic state include a Hall carrier density that initially tracks the number of doped holes and the emergence of an anisotropic pseudogap; the latter characterised by disconnected Fermi arcs, closure at a critical doping level $p^* \approx 0.19$, and, in some cases, a strongly enhanced carrier effective mass. In Sr$_2$IrO$_4$, a spin-orbit-coupled Mott insulator often regarded as a 5$d$ analogue of the cuprates, surface probes have revealed the emergence of an anisotropic pseudogap and Fermi arcs under electron doping, though neither the corresponding $p^*$ nor bulk signatures of pseudogap closing have as yet been observed. Here, we report electrical transport and specific heat measurements on Sr$_{2-x}$La$_x$IrO$_4$ over an extended doping range 0 $\leq x \leq$ 0.20. The effective carrier density $n_{\rm H}$ at low temperatures exhibits a crossover from $n_{\rm H} \approx x$ to $n_{\rm H} \approx 1+x$ near $x$ = 0.16, accompanied by \textcolor{blue}{a five-orders-of-magnitude increase in conductivity} and a six-fold enhancement in the electronic specific heat. These striking parallels in the bulk pseudogap phenomenology, coupled with the absence of superconductivity in electron-doped Sr$_2$IrO$_4$, disfavour the pseudogap as a state of precursor pairing and thereby narrow the search for the key ingredient underpinning the formation of the superconducting condensate in doped Mott insulators.
title Carrier density crossover and quasiparticle mass enhancement in a doped 5$d$ Mott insulator
topic Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2312.00515