Γ3-Type Lattice Instability and the Hidden Order of URu2Si2

Yanagisawa, Tatsuya; Mombetsu, Shota; Hidaka, Hisao; Arima, Hiroshi; Akatsu, Mitsuhiro; Yasin, S.; Жерлицын, С.; Wosnitza, J.; Huang, Kevin; Maple, M. B.

doi:10.7566/jpsj.82.013601

Cited by 24 publications

(35 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The tendency toward lattice instability with B 1g symmetry is most probably related with the Kondo physics. Interestingly, similar softening effect (of 0.7%) of the elastic constant (C 11 − C 12 )/2 in the same symmetry (B 1g ≡ Γ 3 ) has been reported below 120 K by ultrasound velocity measurements 31 . In addition, they show that this effect disappears when high magnetic field of 35 T is applied along the c axis.…”

Section: Resultsmentioning

confidence: 57%

“…Raman scattering 30 mainly reported temperature dependence of the intensity of the fully-symmetric phonon mode and optical conductivity studies were mostly focused on the electronic properties. A more detailed study by ultrasonic measurements versus temperature and under high magnetic field 31,32 reported a softening of the elastic constant C 11 − C 12 below ∼ 120 K suggesting a B 1g -type (or Γ 3 ) lattice instability in connection with the Kondo cross-over. Quite recently, an anomalous phonon softening below T 0 in the [1,1,0] direction has been reported by inelastic neutron scattering 33 , calling on for further detailed studies.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Lattice dynamics of the heavy-fermion compoundURu2Si2

et al. 2015

View full text Add to dashboard Cite

We report a comprehensive investigation of the lattice dynamics of URu2Si2 as a function of temperature using Raman scattering, optical conductivity and inelastic neutron scattering measurements as well as theoretical ab initio calculations. The main effects on the optical phonon modes are related to Kondo physics. The B1g (Γ3 symmetry) phonon mode slightly softens below ∼100 K, in connection with the previously reported softening of the elastic constant, C11 − C12, of the same symmetry, both observations suggesting a B1g symmetry-breaking instability in the Kondo regime. Through optical conductivity, we detect clear signatures of strong electron-phonon coupling, with temperature dependent spectral weight and Fano line shape of some phonon modes. Surprisingly, the line shapes of two phonon modes, Eu(1) and A2u(2), show opposite temperature dependencies. The A2u(2) mode loses its Fano shape below 150 K, whereas the Eu(1) mode acquires it below 100 K, in the Kondo cross-over regime. This may point out to momentum-dependent Kondo physics. By inelastic neutron scattering measurements, we have drawn the full dispersion of the phonon modes between 300 K and 2 K. No remarkable temperature dependence has been obtained including through the hidden order transition. Ab initio calculations with the spin-orbit coupling are in good agreement with the data except for a few low energy branches with propagation in the (a,b) plane.

show abstract

Section: Resultsmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Lattice dynamics of the heavy-fermion compoundURu2Si2

et al. 2015

View full text Add to dashboard Cite

show abstract

“…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 .…”

Section: Discussionmentioning

confidence: 94%

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

et al. 2014

View full text Add to dashboard Cite

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.

show abstract

“…This indicates that the lowtemperature electronic state of URu 2 Si 2 exhibits a lattice instability with 3 symmetry (x 2 -y 2 -type) that is strongly related to the origin of the hybridized electronic state and the HO. 12 In the present work, we explore a wider temperature range from 1.5 to 116 K up to 61. 8 procedure described in more detail in Ref.…”

mentioning

confidence: 99%

“…8 procedure described in more detail in Ref. 12. For the present measurements, long-pulsed magnetic fields with a duration of ∼150 ms and a maximum field of 61.85 T have been used.…”

mentioning

confidence: 99%

Hybridization-driven orthorhombic lattice instability in URu2Si2

et al. 2013

View full text Add to dashboard Cite

We have measured the elastic constant (C 11 -C 12 )/2 in URu 2 Si 2 by means of high-frequency ultrasonic measurements in pulsed magnetic fields H [001] up to 61.8 T in a wide temperature range from 1.5 to 116 K. We found a reduction of (C 11 -C 12 )/2 that appears only in the temperature and magnetic field region in which URu 2 Si 2 exhibits a heavy-electron state and hidden order. This change in (C 11 -C 12 )/2 appears to be a response of the 5f electrons to an orthorhombic and volume conservative strain field xx -yy with 3 symmetry. This lattice instability is likely related to a symmetry-breaking band instability that arises due to the hybridization of the localized f electrons with the conduction electrons and is probably linked to the hidden-order parameter of this compound. DOI: 10.1103/PhysRevB.88.195150 PACS number(s): 71.27.+a, 62.20.de, 62.65.+k The heavy-fermion compound URu 2 Si 2 exhibits a secondorder phase transition involving uranium's 5f -electron state at T o = 17.5 K, and also exhibits unconventional superconductivity at T c ∼ 1.4 K. Though the transition at T o shows clear anomalies in several thermodynamic quantities, 1-3 the order parameter has not been identified microscopically for more than a quarter of a century; thus, the unknown transition has been called "hidden order (HO)." 4In high magnetic fields (using static or pulsed magnetic field) for H [001] at low temperatures, URu 2 Si 2 undergoes three metamagnetic transitions in the range 35 and 39 T with a collapse of the HO phase, [5][6][7] where the c-axis magnetization increases in three steps and reaches a value of ∼1.5 μ B /U at 60 T and 1.5 K, which is approximately half of the value expected from the localized 5f -electron state of U 3+ (3.62 μ B ) or U 4+ (3.58 μ B ). In addition, the electrical resistivity shows an abrupt decrease above 40 T. This suggests that tuning URu 2 Si 2 by means of a magnetic field decreases the hybridization between 5f and conduction electrons, and, therefore, leads to a reduced effective electron mass. 6,7 Given this situation, it is plausible that the hybridized-electron state observed at low-temperature and in low-magnetic-field regions will change to a relatively light Fermi-liquid state when a high magnetic field is applied along the [001] axis as indicated by the disappearance of the heavy band.7 Thus, the collapse of the HO and the drastic change of the 5f electronic state appear to be strongly connected and suggest that the order parameter of the HO phase is veiled in the screening of the localized 5f electronic state via their strong hybridization with conduction electrons states.In contrast, several recent theoretical models predict that the order parameter of the HO phase is of local nature and based on higher-rank electric and magnetic multipoles. [8][9][10] In particular, the xy(x 2 -y 2 ) electric hexadecapole model, which has been proposed by Kusunose and Harima and also partly related to the theory of Haue and Kotliar, 11 suggests that electric quadrupole moments O xy (=J x J y +...

show abstract

Γ₃-Type Lattice Instability and the Hidden Order of URu₂Si₂

Cited by 24 publications

References 30 publications

Lattice dynamics of the heavy-fermion compoundURu2Si2

Lattice dynamics of the heavy-fermion compoundURu2Si2

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

Hybridization-driven orthorhombic lattice instability in URu2Si2

Contact Info

Product

Resources

About