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Quantum-Critical Scale Invariance in Transition Metal Alloy



Yasuyuki Nakajima, Tristin Metz, Christoper Eckberg, Kevin Kirshenbaum, Alex Hughes, Renxiong Wang, Limin Wang, Shanta Saha


Quantum-mechanical fluctuations between competing phases at Τ = 0 induce exotic finite-temperature collective excitations that are not described by the standard Landau Fermi liquid framework [1-4]. These excitations exhibit anomalous temperature dependences, or non-Fermi liquid behavior, in the transport and thermodynamic properties [5] in the vicinity of a quantum critical point, and are often intimately linked to the appearance of unconventional Cooper pairing as observed in strongly correlated systems including the high-Τc cuprate and iron pnictide superconductors [6,7]. The presence of superconductivity, however, precludes direct access to the quantum critical point, and makes it difficult to assess the role of quantum-critical fluctuations in shaping anomalous finite-temperature physical properties, such as Planckian dissipation h/Tp = kBT [8-10]. Here we report temperature-field scale invariance of non-Fermi liquid thermodynamic, transport and Hall quantities in a non-superconducting iron-pnictide, Ba(Fe1/2Co1/3Ni1/3)d2^As2, indicative of quantum criticality at zero temperature and zero applied magnetic field. Beyond a linear in temperature resistivity, the hallmark signature of strong quasiparticle scattering, we find a move universal Planck-limited scattering rate that obeys a scaling relation between temperature and applied magnetic fields down to the lowest energy scales. Together with the emergence of hole-like carriers close to the zero-temperature and zero-field limit, the scale invariance, isotropic field response and lack of applied pressure sensitivity point to the realization of a novel quantum fluid predicted by the holographic correspondence [11] and born out of a unique quantum critical system that does not drive a pairing instability.
Communications Physics


quantum criticality


Nakajima, Y. , Metz, T. , Eckberg, C. , Kirshenbaum, K. , Hughes, A. , Wang, R. , Wang, L. and Saha, S. (2020), Quantum-Critical Scale Invariance in Transition Metal Alloy, Communications Physics, [online], (Accessed March 1, 2024)
Created October 14, 2020, Updated July 27, 2022