Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session V43: Heavy Fermions and Quantum CriticalityLive
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Sponsoring Units: DCMP Chair: Xiaxin Ding, Idaho National Laboratory |
Thursday, March 18, 2021 3:00PM - 3:12PM Live |
V43.00001: Pressure tuning of CeRhIn5 microstructures Janas Kunnelakat John, Maja Bachmann, Filip Ronning, Eric D Bauer, Joe Thompson, Philip Moll, Michael Nicklas We revisited the temperature-pressure (T−p) phase diagram of CeRhIn5 utilizing microstructures to probe the electrical resistivity for well-defined crystalline directions along the a- and c-axes of the tetragonal structure. At ambient pressure CeRhIn5 orders antiferromagnetically below 3.8K. Application of external pressure suppresses the antiferromagnetism and induces an unconventional superconducting (SC) state. The T−p phase diagram obtained on the microstructure resembles that of bulk single crystals. Initially, we observe broad SC transitions in resistivity, which sharpen upon approaching the maximum of the SC dome. The electrical resistivity data in the transition region follows the predictions of the Berezinskii-Kosterlitz-Thouless theory proposed for 2D superconductors, e.g. we find the characteristic non-linear I-V curves for current applied along both a- and c- axes. The latter is not expected for CeRhIn5 and puts a purely intrinsic origin of the 2D superconductivity related to 2D antiferromagnetic fluctuations in question. That is supported by finite element analysis of strain-fields in the microstructure. Therefore, we speculate that the observed features of 2D superconductivity in CeRhIn5 may have an origin in a combination of intrinsic and extrinsic effects. |
Thursday, March 18, 2021 3:12PM - 3:24PM Live |
V43.00002: Competing interactions in the quasi-2D heavy fermion Ce2RhIn8 Travis Williams, Barry Winn, Filip Ronning, Eric D Bauer The heavy fermion family CenMIn3n+2 (M = Co, Rh, In with n = 1,2…∞) consists of n layers of CeIn3 stacked along the c-axis, with a spacer layer of MIn2. This allows for a discrete tuning of the electronic structure from quasi-2D (n = 1) to fully 3D (n = ∞). The n = 2 compound Ce2RhIn8 forms an important member of the family with intermediate dimensionality. Here, we use time-of-flight neutron scattering to probe the magnetic interactions in Ce2RhIn8 in order to probe the effect of reduced dimensionality on the magnetic coupling. We find a canted antiferromagnetic structure with a moment size comparable to what is seen for CeRhIn5. Furthermore, we find quasi-elastic scattering that may be the result of the competition between 2D and 3D characteristics. |
Thursday, March 18, 2021 3:24PM - 3:36PM Live |
V43.00003: Magnetoresistance of Sn-substituted CeCoIn5 Nikola Maksimovic, Fanghui Wan, James Analytis Electrical transport in CeCoIn5 exhibits marked similarities with other so-called ‘strange’ metals, including a linear variation of resistivity with temperature. However, among this family, CeCoIn5 has a unique magnetoresistance. In contrast to other strange metals, the magnetoresistance of CeCoIn5 exhibits a non-monotonic variation with the field, the origin of which is not well-understood. In this talk, magnetoresistance measurements of CeCoIn5 and Sn-substituted CeCoIn5 will be presented. We find that the magnetoresistance of CeCoIn5 is strongly affected by Sn-substitution, transitioning to more conventional metallic behavior as the Sn-substitution level increases. These findings will be discussed in the context of recent evidence for a quantum critical point induced by Sn-substitution in this material. |
Thursday, March 18, 2021 3:36PM - 3:48PM Live |
V43.00004: Phase diagram and Fermi surface of CeOs4Sb12 under pressure Kathrin Goetze, Matthew Pearce, Matthew J Coak, Paul Goddard, William A Coniglio, Audrey Grockowiak, Stanley W Tozer, David E Graf, M Brian Maple, Matthew Brown, Pei-Chun Ho, John Singleton The skutterudite CeOs4Sb12 exhibits an unusual phase diagram in which the boundary of the field-tuned valence transition between L and H phase takes a wedge-like shape as opposed to the expected elliptical behavior. A quantum critical point (QCP) associated with the field-induced suppression of the low-temperature ordered spin density wave (SDW) phase is thought to be responsible for this anomalous behavior [1, 2]. |
Thursday, March 18, 2021 3:48PM - 4:00PM Live |
V43.00005: Physical properties of Ce3+xRu4Sn13-x (0 ≤ x ≤ 1) single crystals Jeonghun Lee, Eundeok Mun The heavy fermion systems CeRuSn3 and Ce3Ru4Sn13 crystallize into the cubic LaRuSn3- and Yb3Rh4Sn13-type structure, respectively, having the same space group (Pm-3n, No. 223). Earlier studies on polycrystalline samples show that the electrical resistivity ρ(T) of Ce3Ru4Sn13 follows a metallic behavior, whereas ρ(T) of CeRuSn3 shows a semiconducting-like behavior. In this study, we have grown single crystals of Ce3+xRu4Sn13-x (0 ≤ x ≤ 1) by Sn flux. Physical property measurements are performed in these single crystals on various samples with different growth conditions. Thermodynamic and transport properties of these single crystals highly depend on the initial loading compositions, showing either a typical Kondo lattice behavior or a semiconducting-like behavior. In this talk, we will present the crystal structure of grown single crystals and the relationship between LaRuSn3- and Yb3Rh4Sn13-type structure. In addition, we will discuss drastically different physical properties with respect to crystal structure types. |
Thursday, March 18, 2021 4:00PM - 4:12PM Live |
V43.00006: Heavy fermion behavior in single crystal Pr0.5Ir4Sb10.2Sn1.8 Matthew Cook, Clement Burns Pr based filled skutterudites have proven to be immensely useful in understanding strongly correlated electrons and their interesting low temperature behavior. We have synthesized and measured single crystals of Pr0.5Ir4Sb10.2Sn1.8 [1], a compound based on Zintl electron counting rules. Investigations show heavy fermion behavior in the resistivity, specific heat, and magnetization, with a small superconducting fraction (<1%) also evidenced by resistivity and magnetization. Screening of 4f moments by conduction electrons is made apparent by a logarithmic upturn in the resistivity, the field dependence of the specific heat, and a careful analysis of the nuclear specific heat contribution. This material closely follows the Kadowaki-Woods ratio A/γ2 ≈10-5 μΩcm(K mol/mJ)2. Magnetoresistance measurements show broad and kinked superconducting transitions that suggest multiple superconducting domains. We also discuss the possibility that the superconducting fraction is of reduced dimensionality or from an impurity phase. |
Thursday, March 18, 2021 4:12PM - 4:24PM Live |
V43.00007: Quantum nematicity in EuB6 Gabrielle Beaudin, William Witczak-Krempa, Andrea Bianchi Our experimental discovery of a quantum nematic phase in the colossal magnetoresistive material EuB6 constitutes a breakthrough in quantum material research. Unlike the quantum nematics in the cuprate and arsenide superconductors, there is no nearby lattice instability complicating the interpretation, making EuB6 a clean model system for studying electronic nematicity. Interestingly, the nematic appears in the same region of the temperature-magnetic field phase diagram where experiments indicate magnetic polarons. This not only indicates a new understanding of nematicity but also paves the way for obtaining novel magnetoresistive transistor action in spintronic devices. |
Thursday, March 18, 2021 4:24PM - 4:36PM Live |
V43.00008: Frustration and quantum first-order transitions in trimer quantum magnets Lukas Weber, Stefan Wessel Frustration in quantum magnets gives rise to many complex phase diagrams and phenomena. Yet, especially in higher dimensions, their unbiased treatment still poses a challenge. In the case of quantum Monte Carlo methods, such as the stochastic series expansion (SSE), large-scale simulations are hindered by the negative-sign problem. However, for certain models, a sign-free basis is known exactly. In this work, we extend this set to lattices comprised of fully-frustrated spin trimers. Using the SSE, we simulate two different spin-trimer models and investigate the role of the spin-chirality degree of freedom internal to each frustrated trimer. For the square lattice of triangles, we refute earlier claims of chirality order, whereas in the fully-frustrated trilayer limit, the chirality induces a macroscopic jump in the entropy at a quantum first-order phase transition. These results advance the understanding of frustrated models with multicomponent local Hilbert spaces and increase the applicability of Monte Carlo methods in these systems. |
Thursday, March 18, 2021 4:36PM - 4:48PM Live |
V43.00009: Non-unitary dynamics of 2+1d free Fermions: Emergent quantum criticality Qicheng Tang, Xiao Chen, Wei Zhu We investigate non-unitary random dynamics of 2+1d free Fermion models. Compared to unitary dynamics where the system is evolved towards equilibration with a volume-law entanglement, the additional imaginary non-unitary dynamics leads to a dynamical steady state that displays a unique entanglement scaling behavior similar to that of a Fermi liquid ground state. Besides, both the mutual information and squared two-point correlation function of the steady state exhibit a typical power-law scaling. Thus, our results demonstrate a novel approach towards quantum criticality via a specified non-unitary random dynamics. |
Thursday, March 18, 2021 4:48PM - 5:00PM Live |
V43.00010: Formation of short-range magnetic order and avoided ferromagnetic quantum criticality in pressurized LaCrGe3 Elena Gati, John Wilde, Rustem Khasanov, Li Xiang, Sachith Dissanayake, Ritu Gupta, Masaaki Matsuda, Feng Ye, Bianca Haberl, Udhara Kaluarachchi, Robert J McQueeney, Andreas Kreyssig, Sergey Budko, Paul C Canfield LaCrGe3 has emerged as a model system for the study of the avoidance of ferromagnetic (FM) quantum criticality in itinerant magnets [1,2]. In this talk, we will present our results from combining thermodynamic, transport, x-ray and neutron scattering as well as μSR measurements on LaCrGe3 under pressure to identify the various phases in the phase diagram across the avoided FM quantum-critical point. We present thermodynamic evidence (i) for the first-order character of the FM transition at lowest temperatures and (ii) for the formation of new phases at high pressures. From our microscopic data, we infer that short-range FM ordered clusters rather than long-range modulated antiferromagnetism exist in these high-pressure phases. Overall, our results suggest that the phase diagram of LaCrGe3 combines features that are usually associated with avoided criticality in either clean or strongly disordered FM metals. |
Thursday, March 18, 2021 5:00PM - 5:12PM Live |
V43.00011: Magnetic Structures in the Vicinity of the Pressure-Induced Superconducting Phase in CeNiC2 Depei Zhang, Hanming Ma, Jun Gouchi, Feng Ye, Takahiro Matsuoka, Yoshiya Uwatoko, Masaaki Matsuda The Ce-based non-centrosymmetric strongly correlated electron system, CeNiC2, shows multiple magnetic phase transitions at low temperatures [1]. Most importantly, we have recently observed the pressured-induced heavy-fermion superconductivity in this compound below 3.5 K under 10.7 and 11GPa [2]. However, the magnetic structures of CeNiC2 have not been well studied. In order to understand the superconducting pairing mechanism, it is important to characterize the magnetic structures in the vicinity of the superconducting phase. This talk will focus on the high-pressure magnetic structure study of CeNiC2 based on our unpolarized and polarized neutron diffraction experiments using single crystals. An incommensurate antiferromagnetic phase (AFIC), in which the magnetic structure depends on pressure, is observed in a wide pressure range. The temperature and pressure dependent magnetic structures in the AFIC phase and their connections to the superconductivity will be discussed in detail. |
Thursday, March 18, 2021 5:12PM - 5:24PM Live |
V43.00012: Evolution of the electronic structure of CeCoIn5 across a quantum critical point Daniel Eilbott, Ping Ai, Yi Lin, Samuel Ciocys, Nikola Maksimovic, Fanghui Wan, Jonathan Denlinger, James Analytis, Alessandra Lanzara The existence and nature of a possible quantum critical point in CeCoIn5 have been under debate for many years. Recent work has focused on the details of f-c hybridization in the evolution of the Kondo lattice as a function of temperature. Here we report a doping- and temperature-dependent study of CeCoIn5 by angle-resolved photoemission spectroscopy. Changes to the electronic structure with both doping and temperature, as well as the possible existence of a quantum critical point, are discussed. |
Thursday, March 18, 2021 5:24PM - 5:36PM Live |
V43.00013: The Hall Effect and Dynamical Scaling about the Quantum Critical Point in Elemental Chromium Stephen Armstrong, Daniel Marc Silevitch, Thomas F Rosenbaum Elemental chromium is a spin-density-wave (SDW) antiferromagnet that can be tuned through a second order quantum phase transition by the application of 10 GPa of pressure. A nesting condition in the paramagnetic Fermi surface partially gaps the Fermi surface and forms the SDW. Since the Hall coefficient directly probes properties of the Fermi surface, it is an effective tool to investigate the evolution of the Fermi surface in the quantum critical regime, where there are indications of strong-coupling physics. In the low temperature limit, the Hall coefficient varies rapidly with pressure across the quantum critical point. By extending this measurement to higher temperatures, we are able to track the P-T dependence of this crossover and test analogies to the pseudogap phase in the superconducting cuprates. The temperature dependence of the width of this crossover constrains theories of dynamical scaling at the quantum critical point. |
Thursday, March 18, 2021 5:36PM - 5:48PM Live |
V43.00014: Universality and quantum criticality in quasiperiodic spin chains Utkarsh Agrawal, Sarang Gopalakrishnan, Romain Vasseur Quasiperiodic systems are aperiodic but deterministic, so their critical behavior differs from that of clean systems and disordered ones as well. Quasiperiodic criticality was previously understood only in the special limit where the couplings follow discrete quasiperiodic sequences. Here we consider generic quasiperiodic modulations; we find, remarkably, that for a wide class of spin chains, generic quasiperiodic modulations flow to discrete sequences under a real-space renormalization-group transformation. These discrete sequences are therefore fixed points of a functional renormalization group. This observation allows for an asymptotically exact treatment of the critical points. We use this approach to analyze the quasiperiodic Heisenberg, Ising, and Potts spin chains, as well as a phenomenological model for the quasiperiodic many-body localization transition. |
Thursday, March 18, 2021 5:48PM - 6:00PM Live |
V43.00015: First Principles Study on Pressure Induced Valence Transition in Eu-based Compounds Young-Joon Song, Roser Valenti Compounds having localized 4f electrons have been extensively studied due to their interesting properties such as the Kondo effect, topological properties, and superconductivity. In particular, the effect of pressure plays a key role to induce a phase transition in these 4f compounds. For example, in magnetic 4f compounds, the critical pressure can suppress their magnetism, which is well-known as the Doniac phase diagram. In this presentation, we will focus on the tetragonal magnetic Eu-based compounds. In many cases, Eu-based compounds show divalent electronic states and magnetic ordering at low temperatures. However, it has been reported that both pressure and temperature can change these electronic states to be trivalent. Consequently, this valence transition leads to vanishing magnetism. Using first-principles calculations and model Hamiltonians, we will address the mechanism of the pressure-induced valance transition on the tetragonal magnetic Eu-based compounds. |
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