Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session B44: Cerium 115 and Related Compounds |
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Sponsoring Units: DCMP Chair: Filip Ronning, Los Alamos Natl Lab Room: LACC 504 |
Monday, March 5, 2018 11:15AM - 11:27AM |
B44.00001: Band dependent inter-layer f-electron hybridization in CeRhIn5 Qiuyun Chen, Difei Xu, Xiaohai Niu, Rui Peng, Hai chao Xu, Chenhaoping Wen, Yongjun Zhang, Huiqiu Yuan, Honh Lee, Shiyong Tan, Jian-Xin Zhu, Sefan Kirchner, Donglai Feng A key issue in heavy fermion research is how subtle changes in the hybridization between the 4f (5f) and conduction electrons can result in fundamentally different ground states. CeRhIn5 stands out as a particularly notable example-- replacing Rh by either Co or Ir, located above or below Rh in the periodic table, antiferromagnetism gives way to superconductivity. In this photoemission study of CeRhIn5, we demonstrate that the use of resonant ARPES with polarized light allows to extract detailed information on the 4f crystal field states together with details on the 4f and conduction electrons hybridization which together determine the ground state. We directly observe weakly dispersive Kondo resonances of f-electrons and identify two of the three Ce 4f15/2 crystal-electric-field levels. In particular, we observe band-dependent hybridization, which directly relates to the fact that the hybridization occurs primarily between the Ce 4f states in the CeIn3 layer and two more three-dimensional bands composed of the Rh 4d and In 5p orbitals in the RhIn2 layer. Our results allow to connect the properties observed at elevated temperatures with the unusual low-temperature properties of this enigmatic heavy fermion compound. |
Monday, March 5, 2018 11:27AM - 11:39AM |
B44.00002: Mechanism of strange superconductivity on Kondo lattice: application for CeMIn5 (M=Co,Rh) Yung-Yeh Chang, Feng Hsu, Stefan Kirchner, Chung-Yu Mou, Joe Thompson, Ting-Kuo Lee, Chung-Hou Chung The heavy-fermion CeMIn5 family with M = Co, Rh provide a paradigm example of strange superconductivity with d−wave pairing and a non-Fermi liquid (strange metal, SM) normal state, emerged near an antiferromagnetic quantum critical point (QCP). The microscopic mechanism of strange superconductivity as well as its link to quantum criticality and strange metal behaviour are still long-standing un-resolved open issues. Recent ARPES and STM measurements indicate important roles played by both Kondo hybridization and antiferromagnetic fluctuations among f−electrons. We offer a microscopic mechanism to address these issues based on a competition and coexistence between Kondo hybridization and antiferromagnetic resonanting valence-bond (RVB) spin liquid in the Kondo-Heisenberg model on a quasi-2d lattice. The competition between the two leads to a Kondo breakdown QCP, while the co-existence gives rise to superconductivity. Our results via a large-N mean-field and effective field theory combined with renormalization group approaches explain remarkably well the observed normal state SM behaviors near criticality and how superconductivity is developed from it. |
Monday, March 5, 2018 11:39AM - 11:51AM |
B44.00003: Direct observation of a quasiparticle band in the antiferromagnetic Kondo lattice CeIn3 Yun Zhang, Qiuyun Chen The electronic structure of the In layer-terminated Kondo lattice CeIn3 has been studied by on-resonant angle-resolved photoemission spectroscopy with improved resolution. A weakly dispersive quasiparticle band has been observed directly with an energy dispersion of 4 meV, indicating the existence of weak hybridization between the f electrons and conduction electrons. Both the conduction bands (α and β) and f band exhibit the same dichroic response to different circularly polarized lights, providing a prerequisite for the hybridization between them. The c-f hybridization strength in CeIn3 is much weaker than in the more two-dimensional compounds CeCoIn5 and CeIrIn5. Our results suggest that the 4f states in CeIn3 are dominated by the localized character, with a small itinerant component. |
Monday, March 5, 2018 11:51AM - 12:03PM |
B44.00004: Fermi Surface Nesting in CeIn3 Revealed by Neutron Spectroscopy Marc Janoschek, David Fobes, Filip Ronning, Eric Bauer, Cristian Batista We report a high-resolution neutron spectroscopy study of the archetypal heavy fermion material CeIn3 that exhibits an antiferromagnetic ground state below TN = 10.1 K with a commensurate propagation vector k = (½, ½, ½). Previous neutron results with moderate energy resolution reported a substantial spin gap of 1.3 meV, which suggest large magnetic anisotropy even though this is not supported by the observed bulk properties. Our results unambiguously demonstrate that CeIn3 does not exhibit a spin gap. Instead, we find that the spin waves disperse quasi-vertically up to almost 1 meV. When such as steep dispersion is probed with not sufficiently high resolution, this will result in an artifact in the neutron spectrum that looks like a spin gap, and thus our findings are in agreement with previous reports. More interestingly, the steep spin wave dispersion of CeIn3 reveals truly long-range magnetic exchange interactions and suggests Fermi surface nesting. |
Monday, March 5, 2018 12:03PM - 12:15PM |
B44.00005: Impurity-induced magnetic droplet in unconventional superconductors near magnetic instability: Application to Nd doped $\mathbf{CeCoIn_5}$ Shizeng Lin, Jian-Xin Zhu The intricate interplay between magnetism and superconductivity represents one of main challenges in strongly correlated electronic systems. Based on the phenomenological and microscopic modeling, we show that for the Pauli limited $d$-wave superconductors in the vicinity of SDW instability relevant for Nd doped $\mathrm{CeCoIn_5}$, magnetic impurities locally induce droplets of SDW order. At zero field, the Nd impurity spins are along the $c$ axis due to the coupling to the conduction electrons with an easy $c$ axis, besides their own crystal field effect. The in-plane magnetic field cants the impurity moments toward the $ab$ plane, which suppress the droplets of SDW order. At high fields, the long-range SDW inside the superconducting phase is stabilized as a consequence of magnon condensation. Our results are consistent with the recent neutron scattering and thermal conductivity measurements for the Nd doped $\mathrm{CeCoIn_5}$. |
Monday, March 5, 2018 12:15PM - 12:27PM |
B44.00006: Intertwined Orders in CeCoIn5: Neodymium Doping Study Duk Young Kim, Roman Movshovich, Shizeng Lin, Franziska Weickert, Priscila Rosa, Eric Bauer, Filip Ronning, Joe Thompson We measures thermal conductivity measurements on Ce0.95Nd0.05CoIn5 with magnetic field rotating in the a-b plane of this tetragonal compound. The step in thermal conductivity when field is rotated through antinodal [100] direction of superconducting d-wave order parameter with the high field low temperature (HFLT) phase demonstrates robustness of the triply intertwined orders (of pure CeCoIn5) against 5% Nd doping. The hysteresis in the data as a function of field magnitude reveal signatures of a p-wave pair density wave (PDW) in the low field SDW phase as well. Given different origins and properties of the SDW and HFLT states, the presence of three intertwined orders in both phases emphasizes that the presence of p-wave PDW is ubiquitous in the company of coupled superconducting d-wave and magnetic SDW orders, suggesting the general nature of this phenomenon. |
Monday, March 5, 2018 12:27PM - 12:39PM |
B44.00007: Thermal expansion measurements of CeRhIn5 at extremes Priscila Rosa, Sean Thomas, Fedor Balakirev, Jonathan Betts, Soonbeom Seo, Filip Ronning, Eric Bauer, Joe Thompson, Marcelo Jaime The heavy-fermion antiferromagnet CeRhIn5 exhibits remarkable behavior when subjected to either high magnetic fields or high applied pressures. From the superconducting dome around a putative unconventional quantum critical point at 2.3 GPa to the recently discovered XY nematic phase at 28 T, this material hosts important open questions. In this talk, we will discuss the properties of CeRhIn5 at these extremes via thermal expansion and magnetostriction measurements. We use optical fibers containing fiber Bragg grating (FBG) sensors to measure the strain in millimiter-sized single crystals subjected to DC fields to 45 T. We also describe an FBG optical apparatus for measuring thermal expansion under applied hydrostatic pressures to 2.5 GPa. |
Monday, March 5, 2018 12:39PM - 12:51PM |
B44.00008: Non-Fermi Liquid Transport in CeCo(In1-xCdx)5 Nikola Maksimovic, Ian Hayes, Sooyoung Jang, James Analytis The heavy fermion superconductor CeCoIn5 has drawn attention due the presence of unconventional superconductivity existing near a quantum critical point, a situation reminiscent of the high-Tc cuprates and iron-based superconductors. In contrast to many other quantum critical metals, this compound exists in proximity to a putative field-tuned quantum critical point with repercussions for the non-Fermi liquid transport at finite temperatures. In this study, we search for electronic transport scaling relations in the non-fermi liquid regime in CeCo(In1-xCdx)5. |
Monday, March 5, 2018 12:51PM - 1:03PM |
B44.00009: Exploring electronic and magnetic anisotropy with thermal expansion and uniaxial strain in CeRhIn5 Sean Thomas, Paul Tobash, Adam Dioguardi, Matthew Curtis, Joe Thompson, Priscila Rosa, Eric Bauer, Filip Ronning The heavy-fermion material CeRhIn5 orders antiferromagnetically at 3.8 K in zero magnetic field. Recent high-field measurements discovered an electronic nematic-like state at 28 Tesla for fields applied at a slight tilt from the c-axis. Low-fields applied in the ab-plane also show a rich HT-phase diagram, where neutron scattering measurements have revealed a strongly field dependent spin anisotropy. Here, we explore the correlation between the high-field nematic phase and the low-field magnetic phases using a combination of thermal expansion and uniaxial strain measurements. |
Monday, March 5, 2018 1:03PM - 1:15PM |
B44.00010: T-dependent f-states in CeRhIn5 Jonathan Denlinger, Sooyoung Jang, James Allen, M Brian Maple, Bo-Gyu Jang, Ji Hoon Shim CeRhIn5, an antiferromagnet below 3.8K, is considered to exhibit fully localized Ce 4f behavior based on agreement of dHvA orbit sizes of α and β Fermi surface (FS) sheets to non-f LaRhIn5 dHvA and to f-localized DFT calculations. Consistent with dHvA, we find using f-resonant angle-resolved photoemission (ARPES) negligible signatures of f-d hybridization at EF for the α and β bands. However, contrary to the fully localized scenario, strong Kondo-like Ce 4f spectral weight is found in a shallow electron band corresponding to the third γ FS sheet in CeRhIn5. The Ce 4f amplitude exhibits log(T) dependence above 50K up to 200K, similar to previous T-dependent measurements for CeCoIn5 [1], and a change in the shape of the γ FS between low and high T is detected. The origins of this momentum-dependent participation of Ce 4f weight in the Fermi surface is theoretically investigated using first principles dynamical mean field theory (DMFT) calculations. The effects of in-plane versus out-of-plane Ce-In f-p hybridization and flattening of the ground state f-orbital for CeRhIn5 compared to CeCoIn5 and CeIrIn5 are discussed. |
Monday, March 5, 2018 1:15PM - 1:27PM |
B44.00011: Anisotropy studies in microstructured Ce-115 heavy fermion superconductors Toni Helm, Maja Bachmann, Kent Shirer, Kimberly Putkonen, Tino Zimmerling, Amelia Estry, Xiangwei Huang, Fedor Balakirev, Eric Bauer, Filip Ronning, Philip Moll We recently uncovered the nematic character of a field-induced state in the heavy-fermion superconductor CeRhIn5, emerging at magnetic fields above 30 T and temperatures below 2 K [1]. The in-plane conductivity develops a sudden anisotropy ρa/ρb at low temperatures, which is linked to the magnetic field orientation. This raises questions on the role of magnetic ordering in determining the magnetotransport anisotropy. The 4f-moments of CeRhIn5 order anti-ferromagnetically, while in the related superconductors CeCoIn5 and CeIrIn5 no static magnetic order appears. We systematically investigate the anisotropic magnetotransport in sub-micron sized transport devices fabricated using Focused Ion Beam machining from highest-quality single crystals. We present a comparative analysis of the magnetoresistance anisotropy in Ce(Co,Rh,Ir)In5, and experimentally investigate the role of electronic layeredness in these superconductors. |
Monday, March 5, 2018 1:27PM - 1:39PM |
B44.00012: Anisotropic high-field magnetoresistance of microstructured CeIrIn5 Kent Shirer, Maja Bachmann, Laurel Winter, Fedor Balakirev, Ross McDonald, Eric Bauer, Filip Ronning, Philip Moll We report magnetoresistance up to 65T on high quality, focused ion beam (FIB)-fabricated microstructures of CeIrIn5, a strongly correlated metal known for its heavy-fermion superconducting state at Tc ~ 0.4K. We probe the anisotropic magnetotransport in microstructured samples with well-defined geometries, and we simultaneously measure resistance along the [100] and [001] directions with respect to a number of applied filed orientations. We observe a jump-like increase of the magnetoresistance in high fields above 40T for a narrow range of field angles. The transport anomaly is reminiscent of recent transport observations in CeRhIn5. Yet, unlike CeRhIn5, CeIrIn5 does not order anti-ferromagnetically; thus, our results point to origins other than metamagnetism. |
Monday, March 5, 2018 1:39PM - 1:51PM |
B44.00013: Kondo Effect in the Antiferromagnetic Quantum Critical Metal Peter Lunts, Sung-Sik Lee We study the effect of a single spin-half magnetic impurity on a two dimensional metal at the antiferromagnetic quantum critical point. We use a field-theoretic functional renormalization group analysis, and perturbatively study the flow of the Kondo coupling in the regime where it is small. The recent low-energy solution of the clean quantum critical theory allows us to access the effects of critical fluctuations in a controlled manner. We find that the Kondo coupling acquires a strong momentum dependence around the Fermi surface due to the enhanced scattering near the hot spots. We comment on physical observables such as the resistivity and the shape of the Kondo cloud, as compared with the Kondo problem in Fermi liquid metals. |
Monday, March 5, 2018 1:51PM - 2:03PM |
B44.00014: Kondo destruction in multipolar order: Implications for heavy-fermion quantum criticality Qimiao Si, Hsin-Hua Lai, Emilian Nica, Wenjun Hu, Shoushu Gong Motivated by the quantum-critical heavy-fermion systems [1,2] exhibiting multipolar orders, we theoretically study an effective field theory of a Kondo lattice model involving both spin and quadrupole degrees of freedom. The field theory contains a quantum non-linear sigma model of the antiferroquadrupolar (AFQ) phase in spin-1 systems, with Kondo couplings to conduction electrons. In the absence of the Kondo coupling, we demonstrate the stability of the AFQ phase using density matrix renormalization group analysis in the underlying spin model. We proceed to analyze the effect of the Kondo couplings, using a mixed fermion-boson renormalization group procedure [3]. We show that the Kondo couplings are exactly marginal, which implies a Kondo destruction in the multipolar phase. Our results provide theoretical basis for the recently advanced notion of sequential Kondo-destruction [1]. Implications of our results for the global phase diagram of the heavy fermion systems are discussed. [1] V. Martelli et al., arXiv:1709.09376. [2] J. Custers et al, Nat. Mater. 11, 189 (2012). [3] S. J. Yamamoto and Q. Si, Phys. Rev. B 81, 205106 (2010). |
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