Lattice Instability and Elastic Response in the Heavy Electron System URu2Si2

Kuwahara, K.; Arima, Hiroshi; Sakakibara, Toshiro; Сузукі, Осаму; Nakamura, Shintaro; Gotô, Terutaka; Mihalik, M.; Menovsky, A.A.; Visser, A. de; Franse, J.J.M.

doi:10.1143/jpsj.66.3251

Cited by 44 publications

(56 citation statements)

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“…These two data sets are plotted with the same ordinate; the upper axis corresponding to the blue data shows the temperature dependence at 0 T, the lower axis corresponding to the data shows the magnetic-field dependence at 1.5 K. Here, we notice that the elastic-constant change (softening of $0:7%) in the temperature dependence below the local maximum at $120 K is comparable to the increase up to H $ 45 T in the field dependence. Here, the maximum in the elastic constant eventually occurs as a balance between the phonon-background and the softening of strain-susceptibility due to 5f -electron effects in the temperature dependence, 27) while the c-axis magnetization shows a maximum at around T ;max $ 55 K. It should be mentioned that the present temperature dependence is different from the previously reported data, 25) which shows the maximum at $70 K and also the softening $0:2% for ðC 11 À C 12 Þ=2. We consider these differences are due to the recent improvements of the measurement conditions, e.g., using mirror-polished sample, appropriate adhesive agents, and higher frequency (higher directional quality) of the ultrasonic wave.…”

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confidence: 82%

“…24,25) Moreover, the magnetic-field dependence of À À3 for H k ½001 does not show any anomaly at the suppression of the HO, while the calculated c-axis magnetic susceptibility shows a jump at H 1 . These discrepancies simply show the limitations of the present localized-electron model to describe the elastic responses.…”

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confidence: 81%

“…Early studies employing ultrasonic measurements on URu 2 Si 2 uncovered a characteristic decrease (softening) of the elastic constant C 11 and ðC 11 À C 12 Þ=2 with decreasing temperature. 24,25) The softening of C 11 had been explained by Grüneisen coupling due to many-body effects, which appears in the bulk modulus of typical heavy-fermion compounds. This phenomena is the so-called Kondo-volume collapse.…”

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Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

et al. 2013

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We have performed ultrasonic measurements on single-crystalline URu 2 Si 2 with pulsed magnetic fields, in order to check for possible lattice instabilities due to the hybridized state and the hidden-order state of this compound. The elastic constant ðC 11 À C 12 Þ=2, which is associated with a response to the À 3 -type symmetry-breaking (orthorhombic) strain field, shows a three-step increase at H ! 35 T for H k c at low temperatures, where successive meta-magnetic transitions are observed in the magnetization. We discovered a new fact that the absolute change of the softening of ðC 11 À C 12 Þ=2 in the temperature dependence is quantitatively recovered at the suppression of hybridized-electronic state and the hidden order in high-magnetic field for H k c associated with the successive transitions. The present results suggest that the À 3 -type lattice instability, is related to both the emergence of the hybridized electronic state and the hidden-order parameter of URu 2 Si 2 . On the other hand, magnetic fields H k ½100 and [110] enhance the softening of ðC 11 À C 12 Þ=2 in the hidden order phase, while no step-like anomaly is observed up to 68.7 T. We discuss the limitation of the localized-electron picture for describing these features of URu 2 Si 2 by examination of a crystalline electric field model in terms of mean-field theory.KEYWORDS: URu 2 Si 2 , hidden order, elastic constant, ultrasound, pulsed-magnetic field ''What is the primary order parameter and its ordering vector for the hidden order of URu 2 Si 2 ?'' is still an open and controversial question and a longstanding issue of condensed matter physics. 1) URu 2 Si 2 , which crystallizes in the ThCr 2 Si 2 -type tetragonal structure (space group No. 139, I4=mmm), shows an unknown second-order transition at T o ¼ 17:5 K, known as the hidden order (HO) phase, and also a transition into an unconventional superconducting state below T c $ 1:4 K. 1-3) Many theoretical models have been proposed from both localized and itinerant electron pictures in attempts to identify the order parameter of the HO phase. Since 29 Si-NMR and zero-magnetic-field SR measurements have detected little ( 1 G) or no significant internal-magnetic field in the HO phase, 4-6) non-dipolar-type order parameters, e.g., electric quadrupole (rank 2), hexadecapole (rank 4), À 3 -type magnetic octupole (rank 3), or dotriacontapole (rank 5) order parameters, are recently attracting attention. 7-13) Thus far, none of the characteristic signatures of the electric-quadrupole or magnetic-octupole order has been identified in resonant X-ray scattering (under magnetic fields) and neutron scattering under uniaxial stress. 14,15) On the other hand, a nematicity of the electron state in the HO is pointed out, since an in-plane rotational four-fold symmetry breaking is observed in the HO by the magnetic-torque measurement by use of cantilever technique. 16) The interpretation of these experimental results remains controversial.URu 2 Si 2 is also considered a heavy-fermion compound since several ph...

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Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

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“…It has been reported that the temperature dependence of elastic constant (C 11 À C 12 )/2 shows an anomalous softening 31,32 , but we point out that the elastic constants are also Q ¼ 0 quantities, which are hard to couple to the antiferroic high-rank mulitpole orders. This softening may be due to the incommensurate excitations found by neutron experiments 33 , which may also be related to the high-field incommensurate spin density wave phase identified above the critical field of hidden order 34 .…”

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Direct observation of lattice symmetry breaking at the hidden-order transition in URu2Si2

et al. 2014

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Since the 1985 discovery of the phase transition at T HO ¼ 17.5 K in the heavy-fermion metal URu 2 Si 2 , neither symmetry change in the crystal structure nor large magnetic moment that can account for the entropy change has been observed, which makes this hidden order enigmatic. Recent high-field experiments have suggested electronic nematicity that breaks fourfold rotational symmetry, but direct evidence has been lacking for its ground state in the absence of magnetic field. Here we report on the observation of lattice symmetry breaking from the fourfold tetragonal to twofold orthorhombic structure by high-resolution synchrotron X-ray diffraction measurements at zero field, which pins down the space symmetry of the order. Small orthorhombic symmetry-breaking distortion sets in at T HO with a jump, uncovering the weakly first-order nature of the hidden-order transition. This distortion is observed only in ultrapure samples, implying a highly unusual coupling nature between the electronic nematicity and underlying lattice.

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“…Although the microscopic order parameter has not yet been definitively established, a multitude of bulk property measurements indicate that a partial gapping of the Fermi surface is involved in the HO transition. In addition to the BCS-like specific heat anomaly, there are anomalies in the electrical resistivity, magnetic susceptibility [77][78][79], ultrasound [86], thermal expansion [87], and an increase in lattice thermal conductivity [88]. Additional evidence points to the opening of a large gap in the tunneling spectrum [89], the incommensurate spin excitation spectrum [90], and the crossing of the chemical potential by a heavy electron band [91].…”

Section: Uru 2 Simentioning

confidence: 98%

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

et al. 2010

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Standard models for simple metals and insulators often fail for systems based on elements with unstable d-or f -electron shells, where strong electronic correlations can generate new and unexpected states of matter. Such a scenario can often be induced when a magnetic phase transition is tuned to absolute zero temperature by an external control parameter such as chemical composition, pressure or magnetic field. At the resulting quantum critical point (QCP), emergent phenomena, such as unconventional superconductivity and novel magnetic phases are frequently observed. The temperature and energy dependences of the physical properties are also found to deviate from expectations for a simple Fermi liquid. This "non-Fermi-liquid" (NFL) behavior is commonly manifested as weak power laws and logarithmic divergences in the physical properties at low temperatures and is often found in a V-shaped region near a QCP, which has become the "classic" QCP phase diagram. However, there is also a growing number of materials where the NFL behavior either occurs far away from the QCP, within an ordered phase, or may not be associated with any putative QCP. Thus, after nearly 20 years of research, it remains unknown whether NFL physics is universal, or if a multitude of unique subclasses exist. In this article, we review research that has primarily been carried out in our laboratory on systems that exhibit NFL behavior that does not conform to the "classic" QCP scenario.

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Lattice Instability and Elastic Response in the Heavy Electron System URu₂Si₂

Cited by 44 publications

References 37 publications

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

Direct observation of lattice symmetry breaking at the hidden-order transition in URu2Si2

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

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Lattice Instability and Elastic Response in the Heavy Electron System URu2Si2

Cited by 44 publications

References 37 publications

Γ3-Type Lattice Instability and the Hidden Order of URu2Si2

Γ3-Type Lattice Instability and the Hidden Order of URu2Si2

Direct observation of lattice symmetry breaking at the hidden-order transition in URu2Si2

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

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Product

Resources

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Lattice Instability and Elastic Response in the Heavy Electron System URu₂Si₂

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂