A long-standing controversial issue in the quest to understand the superconductivity in cuprates is the nature of the enigmatic pseudogap region of the phase diagram. Especially important is whether ...the pseudogap state is a distinct thermodynamic phase characterized by broken symmetries below the onset temperature T∗ . Here we report torque-magnetometry measurements of anisotropic susceptibility within the ab planes in orthorhombic YBa2 Cu3 Oy with exceptionally high precision. The in-plane anisotropy displays a significant increase with a distinct kink at the pseudogap onset temperature T∗ , showing a remarkable scaling behaviour with respect to T/T∗ in a wide doping range. Our systematic analysis reveals that the rotational symmetry breaking sets in at T∗ in the limit where the effect of orthorhombicity is eliminated. These results provide thermodynamic evidence that the pseudogap onset is associated with a second-order nematic phase transition, which differs from the recently reported charge-density-wave transition that accompanies translational symmetry breaking.
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IJS, NUK, SBMB, UL, UM, UPUK
Abstract
The pseudogap phenomenon in the cuprates is arguably the most mysterious puzzle in the field of high-temperature superconductivity. The tetragonal cuprate HgBa
2
CuO
4+
δ
, with only one CuO
...2
layer per primitive cell, is an ideal system to tackle this puzzle. Here, we measure the magnetic susceptibility anisotropy within the CuO
2
plane with exceptionally high-precision magnetic torque experiments. Our key finding is that a distinct two-fold in-plane anisotropy sets in below the pseudogap temperature
T
*
, which provides thermodynamic evidence for a nematic phase transition with broken four-fold symmetry. Surprisingly, the nematic director orients along the diagonal direction of the CuO
2
square lattice, in sharp contrast to the bond nematicity along the Cu-O-Cu direction. Another remarkable feature is that the enhancement of the diagonal nematicity with decreasing temperature is suppressed around the temperature at which short-range charge-density-wave formation occurs. Our result suggests a competing relationship between diagonal nematic and charge-density-wave order in HgBa
2
CuO
4+
δ
.
The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, characterized by Cooper pairs condensed at finite momentum, has been a long-sought state that remains unresolved in many classes of fermionic ...systems, including superconductors and ultracold atoms. A fascinating aspect of the FFLO state is the emergence of periodic nodal planes in real space, but its observation is still lacking. Here we investigate the superconducting order parameter at high magnetic fields H applied perpendicular to the ab plane in a high-purity single crystal of FeSe. The heat capacity and magnetic torque provide thermodynamic evidence for a distinct superconducting phase at the low-temperature/high-field corner of the phase diagram. Despite the bulk superconductivity, spectroscopic-imaging scanning tunneling microscopy performed on the same crystal demonstrates that the order parameter vanishes at the surface upon entering the high-field phase. These results provide the first demonstration of a pinned planar node perpendicular to H, which is consistent with a putative FFLO state.
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Quantum oscillations in transport and thermodynamic parameters at high magnetic fields are an unambiguous signature of the Fermi surface, the defining characteristic of a metal. Recent observations ...of quantum oscillations in insulating SmB6 and YbB12, therefore, have been a big surprise—despite the large charge gap inferred from the insulating behaviour of the resistivity, these compounds seemingly host a Fermi surface at high magnetic fields. However, the nature of the ground state in zero field has been little explored. Here, we report the use of low-temperature heat-transport measurements to discover gapless, itinerant, charge-neutral excitations in the ground state of YbB12. At zero field, sizeable linear temperature-dependent terms in the heat capacity and thermal conductivity are clearly resolved in the zero-temperature limit, indicating the presence of gapless fermionic excitations with an itinerant character. Remarkably, linear temperature-dependent thermal conductivity leads to a spectacular violation of the Wiedemann–Franz law: the Lorenz ratio is 104–105 times larger than that expected in conventional metals, indicating that YbB12 is a charge insulator and a thermal metal. Moreover, we find that these fermions couple to magnetic fields, despite their charge neutrality. Our findings expose novel quasiparticles in this unconventional quantum state.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Objectives
To examine associations of dietary variety with changes in lean mass and physical performance during a 4-year period in an elderly Japanese population. Design: Four-year prospective study.
...Setting
The Hatoyama Cohort Study and Kusatsu Longitudinal Study, Japan.
Participants
935 community-dwelling Japanese aged 65 years or older.
Measurements
Dietary variety was assessed using a 10-item food frequency questionnaire. Body composition was determined by multifrequency bioelectrical impedance analysis, and physical performance (grip strength and usual gait speed) was measured in surveys at baseline and 4 years later. Longitudinal analysis included only participants who were originally in the upper three quartiles of lean body mass, appendicular lean mass, grip strength, and usual gait speed. The outcome measures were decline in lean body mass, appendicular lean mass, grip strength, and usual gait speed, defined as a decrease to the lowest baseline quartile level at the 4-year follow-up survey. Associations of dietary variety with the outcome measures were examined by logistic regression analysis adjusted for potential confounders.
Results
In the fully adjusted model, the odds ratios for decline in grip strength and usual gait speed were 0.43 (95% confidence interval, 0.19–0.99) and 0.43 (confidence interval, 0.19–0.99), respectively, for participants in the highest category of dietary variety score as compared with those in the lowest category. Dietary variety was not significantly associated with changes in lean body mass or appendicular lean mass.
Conclusion
Among older adults, greater dietary variety may help maintain physical performance, such as grip strength and usual gait speed, but not lean mass.
Objectives
To identify the dietary patterns among community-dwelling Japanese older adults and to explore the association between these patterns and sarcopenia.
Design
Cross-sectional study.
Setting
...Kashiwa city, Chiba prefecture, Japan.
Participants
Community-dwelling older adults (n = 1241) aged 65 years and over who were not eligible for long-term care.
Measurements
Dietary intake was assessed using the brief self-administered diet history questionnaire (BDHQ). Dietary patterns were identified using both principal component analysis and the score on the Japanese diet comprising soybeans and soybean products, fish, vegetables, pickles, mushroom, seaweeds, and fruits. Sarcopenia was defined by the Asian Working Group for Sarcopenia (AWGS) criteria. A binary logistic regression analysis was performed with sarcopenia status as the dependent variable after adjusting for economic status, living alone status, BMI, energy intake, multimorbidity, and physical activity.
Results
Participants’ mean age was 74.6 years, and 52.1% were male. According to AWGS criteria, 5.1% had sarcopenia. Three dietary patterns were identified from the principal component analysis. Dietary pattern 1 (DP1), showed high loadings for fish, tofu, vegetables, and fruits which are similar to the side dishes in a typical Japanese diet. Dietary pattern 2 (DP2) had high factor loadings for fish, rice, and miso soup which are main dishes in a typical Japanese diet. Dietary pattern 3 (DP3) had a high factor loading for noodles. Men with the lowest tertile of DP1 score had a higher likelihood of being sarcopenic (Adjusted odds ratio (AOR) 3.67, 95% confidence interval (CI) 1.20∓11.2). Women with the lowest tertile of DP2 score had a moderate likelihood of being sarcopenic (AOR 2.71, 95%CI 0.99∓7.46). Low adherence to Japanese dietary pattern was associated with prevalence of sarcopenia in both genders.
Conclusion
Adherence to a dietary pattern high in foods characteristic of a Japanese diet including fish, soybean products, vegetables, and fruits was associated with low prevalence of sarcopenia in both genders.
Micronutrients are associated with dementia and cognitive decline among older adults. However, nutritional biomarkers of such decline have not been identified. We attempted to identify nutritional ...biomarkers that were independent risk markers of cognitive decline in a population of older Japanese.
Among 873 cognitively intact adults aged 70 years or older at baseline, 682 (mean age standard deviation, 75.5 4.4 years; women 59.7%) were followed for a period of up to 4 years, and nutritional biomarkers in a blood panel were assessed, namely, red blood cell count, hematocrit, mean corpuscular volume, hemoglobin, total cholesterol, high-density lipoprotein cholesterol, hemoglobin A1c, creatinine, albumin, blood glucose, γ-glutamyl transpeptidase, triglyceride, and white blood cell count. Cognition was assessed by the Mini-Mental State Examination, and cognitive decline was defined as a decrease of at least three points on the Mini-Mental State Examination.
During an average follow-up of 2.7 years, 115 adults (16.9%) developed cognitive decline. After controlling for important confounders, the odds ratios for cognitive decline in the lowest and middle tertiles of red blood cell count were 2.62 (95% confidence interval: 1.44-4.74) and 2.18 (1.20-3.96), respectively, as compared with the highest tertile. The corresponding odds ratios were 1.81 (1.05-3.22) and 1.03 (0.58-1.83), respectively, for high-density lipoprotein cholesterol and 2.06 (1.14-3.77) and 1.02 (0.54-1.94) for albumin.
Low red blood cell count, high-density lipoprotein cholesterol, and albumin were independent risk markers for subsequent cognitive decline in a general population of older adults and may be useful in early clinical screening.
We report a systematic comparison study of 3,5‐di(N‐carbazolyl)tetraphenylsilane (SimCP) and N,N′‐dicarbazolyl‐3,5‐benzene (mCP), which are used as the host materials for phosphorescent blue dopants ...in organic light‐emitting diodes (OLEDs). On the basis of photoexcitation emission spectroscopy, thermal stability analysis, photoelectron analysis, charge transport measurements, and molecular dynamics (MD) simulations, we conclude that the non‐π‐conjugated meta‐substituted triphenylsilyl moiety of SimCP exerts a unique hindering effect on the molecular packing characteristics in the condensed phase. The chemical origin of the superior performance of SimCP over mCP is revealed, and is expected to be helpful for the molecular design of effective host materials for enhancing the performance of blue phosphorescent OLEDs.
Two structurally similar host materials for electrophosphorescent blue dopants, mCP and SimCP (see figure), are systematically compared. The triphenylsilyl group on SimCP does not significantly alter the energy levels but prevents the close‐packing of the molecules in the condensed phase. In contrast, the mCP molecules tend to aggregate, as shown in the figure by the red‐shifting of the emission features, adversely affecting the singlet and triplet energy levels of the material.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
An anapole state that breaks inversion and time-reversal symmetries while preserving translation symmetry of an underlying lattice has aroused great interest as a new quantum state, but only a few ...candidate materials have been reported. Recently, in a spin-orbit coupled Mott insulatorSr2(Ir1−xRhx)O4, the emergence of a possible hidden-order phase with broken inversion symmetry has been suggested atTΩabove the Néel temperature by optical second-harmonic-generation measurements. Moreover, polarized neutron diffraction measurements revealed broken time-reversal symmetry belowTΩ, which was supported by subsequent muon spin relaxation experiments. However, the nature of this mysterious phase remains largely elusive. Here, we investigate the hidden-order phase through the combined measurements of the in-plane magnetic anisotropy with exceptionally high-precision magnetic torque and the nematic susceptibility with elastoresistance. A distinct twofold in-plane magnetic anisotropy along the 110 Ir-O-Ir bond direction sets in below aboutTΩ, providing thermodynamic evidence for a nematic phase transition with brokenC4rotational symmetry. However, in contrast to the even-parity nematic transition reported in other correlated electron systems, the nematic susceptibility exhibits no divergent behavior towardsTΩ. These results provide bulk evidence for an odd-parity order parameter with broken rotational symmetry in the hidden-order state. We discuss the hidden order in terms of an anapole state, in which the polar toroidal moment is induced by two current loops in eachIrO6octahedron of opposite chirality. Contrary to the simplest loop-current pattern previously suggested, the present results are consistent with a pattern in which the intra-unit cell loop current flows along only one of the diagonal directions in theIrO4square.
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In this paper, we describe the fabrication of horizontal and inclined micro-multi-fin structures and discuss the experimental results of the shape transfer to resin material. Using the MEMS ...fabrication process, micro-mold structures with microscale ridge structures and several-hundred-nanometer-sized multi-fin structures at the scale of a morpho butterfly were fabricated on Si substrates. The shape transfer to the resin material was examined using a thermal imprinting process. In both mold types, the resin was injected into the narrow gaps of the multi-fin structures of the mold. It was difficult to release the resin in the horizontal multi-fin from the mold. Conversely, with the inclined-type, the multi-fin shape was successfully transferred to the resin and released without fracture (2 μm pitch ridge structure with a 0.2 μm pitch inclined multi-fin structure). The optical reflection of the inclined molded COP resin was evaluated, exhibiting a light blue reflection.
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