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Title: Quantum criticality associated with dimensional crossover in the iso-electronic series Ca2−xSrxRuO4
Authors: Acharya S.
Dey D.
Maitra, Tulika
Taraphder A.
Published in: Journal of Physics Communications
Abstract: The iso-electronic series, Ca2−x SrxRuO4, is studied within the GGA (and spin-orbit coupled GGA) plus DMFT formalism using the hybridization expansion of continuous time Quantum Monte Carlo (CT-QMC) impurity solver. GGA+DMFT, along with CT-QMC impurity solver we used, provides insights into the retarded electronic correlations at finite temperatures. We use GGA+U and energy considerations at T=0 for complementary understanding of the ground state structural and electronic properties. While the dynamical correlations make Sr2RuO4 a Hund’s metal, they drive Ca2 RuO4 to a Mott insulating ground state. We study the single-particle and two-particle responses at three different points (x=2.0, 0.5, 0.0) to understand the anomalous cross-over from Hund’s metal (x=2.0) to a Mott insulator (x = 0) and observe that a structural distortion is likely to be responsible. Further, dynamical correlations reveal that the band-width (W) of the Hund’s metal is larger than its effective local Hubbard U, and a finite Hund’s coupling JH helps it remain in a bad metallic and nearly spin-frozen state over a large temperature range. Ca2RuO4, though, is driven to the proximity of a Mott transition by the narrowing of band width (U/W>1.5). We show that there is a critical end point of second-order structural transition at x=0.5, where spin fluctuations become critical and follow the scaling of local quantum criticality. We argue that this critical end point of quasi-3D nature is associated with an effective dimensional cross-over from the quasi-2D structures of x=2.0 and x=0.0 end-members. Finally we draw an electronic and magnetic phase diagram in T-x plane with these novel inputs, with a fan like region starting from the quantum critical end point at x=0.5. © 2018 The Author(s).
Citation: Journal of Physics Communications (2018), 2(7): -
Issue Date: 2018
Publisher: Institute of Physics Publishing
Keywords: Dimensional crossover
Electronic structure
Quantum critical scaling
ISSN: 23996528
Author Scopus IDs: 57146457900
Author Affiliations: Acharya, S., Department of Physics, King’s College London, London, WC2R 2LS, United Kingdom, Department of Physics, Indian Institute of Technology,Kharagpur, Kharagpur, 721302, India
Dey, D., Department of Physics, Indian Institute of Technology,Kharagpur, Kharagpur, 721302, India
Maitra, T., Department of Physics, Indian Institute of Technology, Roorkee, Roorkee, 247667, India
Taraphder, A., Department of Physics, Indian Institute of Technology,Kharagpur, Kharagpur, 721302, India, Centre for Theoretical Studies, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
Funding Details: SA would like to acknowledge useful discussions on the first-principles calculations with Monodeep Chakraborty. SA acknowledges discussions with Alex Hewson, J Annett, M S Laad, C Weber and Debraj Choudhury and thanks Arjun Mukerji for help in preparing a diagram. SA acknowledges Simons Many-Electron Collaboration, EPSRC (grants EP/M011631/1), UGC (India) and DD acknowledges DST-Inspire (India) for research fellowships. AT acknowledges research funding from CSIR (India) through the grant number: 03(1373)/16/EMR-II.
Corresponding Author: Acharya, S.; Department of Physics, King’s College LondonUnited Kingdom; email:
Appears in Collections:Journal Publications [PH]

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