Pure nematic quantum critical point accompanied by a superconducting dome
Kousuke Ishida, Yugo Onishi, Masaya Tsujii, Kiyotaka Mukasa, Mingwei Qiu, M. Saito, Yuichi Sugimura, Kohei Matsuura, Yuta Mizukami, K. Hashimoto, T. Shibauchi
Abstract
Significance The notion of the quantum critical point (QCP) is at the core of modern condensed matter physics. Near a QCP of the symmetry-breaking order, associated quantum-mechanical fluctuations are intensified, which can lead to unconventional superconductivity. Indeed, dome-shaped superconducting phases are often observed near the magnetic QCPs, which supports the spin fluctuation–driven superconductivity. However, the fundamental question remains as to whether a nonmagnetic QCP of electronic nematic order characterized by spontaneous rotational symmetry breaking can promote superconductivity in real materials. Here, we provide an experimental demonstration that a pure nematic QCP exists near the center of a superconducting dome in nonmagnetic FeSe <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>−</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> Te x . This result evidences that nematic fluctuations enhanced around the nematic QCP can boost superconductivity.