Search

THz electron spin resonance (ESR) measurements of the spinel compound GeCo2O4, which consists of the Co2+ pyrochlore structure, were performed. The temperature dependence measurements revealed new antiferromagnetic phases, AF1 and AF2, below TN. Moreover, a wide magnetic field range of ESR study using a single crystal at 1.8 K also revealed various field-induced phases due to the competition between the spin–lattice coupling and the spin frustration. Critical field resonances were observed at 5.0 T, 8.6 T, and 11.0 T for B//[111] and 5.1 T, 7.7 T, 11.2 T, and 13.0 T for B//[110] at 1.8 K. Although it became difficult to observe ESR above 86 K, the g-values of Co2+ ions were estimated to be g[111] = 3.34 and g[110] = 3.27 for [111] and [110], respectively, from the observed ESR mode above the saturation field at 1.8 K. Detailed frequency-field diagrams of the ESR modes at 1.8 K suggested the existence of spin–lattice coupling energy of 250 GHz (= 1.03 meV = 12 K) at the critical field resonances. The spin gap mode in the frequency-field diagram at 1.8 K showed excitation energies of E[111] = 1004 GHz (= 4.15 meV = 48 K) and E[110] = 1044 GHz (= 4.32 meV = 50 K) for [111] and [110], respectively. These results will be discussed in connection with the di-tetramer model suggested previously.

In recent years, along with the increasing demand for plastic products and the deepening of academics, mass production, weight reduction, and higher precision are progressing. In the field of design development and production technology, there is an increasing need for analysis technology related to resin flow and behavior in order to solve problems related to quality assurance such as molding defects and product strength. Especially in the resin molding process, it is an important issue to create a quality function that applies the analysis of complex multidimensional information because of the high degree of freedom in product shape and mold structure. In order to solve the quality issues regarding the strength and dimensional stability of resin materials, it is effective to apply the “Functionality Evaluation Method” in robust design which is an analytical evaluation method. In this study, we focus on the function of managing the resin filling density in the mold (the input/output relationship of the melting energy related to the resin filling characteristics) for the optimization of resin strength and dimensional stability. We propose a functional evaluation method with the ideal function of stabilizing the resin filling density based on the original definition of material mechanics. As a result of verification of the proposed method, it was clarified that it is extremely important to make the resin filling density in the mold uniform to stabilize the strength of the resin injection molded product.

Purpose: This study aimed to compare the utility score of dysplastic osteoarthritis of the hip (OA) after different surgical treatments., Methods:In this cross-sectional study, we evaluated the utility scores of 204 patients using the Short Form-6 Dimension., Results: Utility scores of all surgery types were significantly higher than those preoperatively in OA (p, Conclusions: Although THA and osteotomy are effective surgical procedures, lifetime treatment plans should be considered to avoid revision surgery as far as possible.

A dichlorosilane gas and a trichlorosilane gas in ambient hydrogen were evaluated to show their different gas flow motions in a slim vertical cold wall chemical vapor deposition reactor for the Minimal Fab system. This evaluation was performed for improving and controlling the film qualities and the productivities, using two quartz crystal microbalances (QCM) installed at the inlet and exhaust of the chamber by taking into account that the QCM frequency corresponds to the real time changes in the gas properties. Typically, the time period approaching from the inlet to the exhaust was shorter for the trichlorosilane gas than that for the dichlorosilane gas. The trichlorosilane gas was shown to move like plug flow, while the dichlorosilane gas seemed to be well mixed in the entire chamber.

Background The locomotive syndrome risk test was developed to quantify the decrease in mobility among adults, which could eventually lead to disability. The purpose of this study was to establish reference values for the locomotive syndrome risk test for adults and investigate the influence of age and sex. Methods We analyzed 8681 independent community dwellers (3607 men, 5074 women). Data pertaining to locomotive syndrome risk test (the two-step test, the stand-up test, and the 25-question geriatric locomotive function scale [GLFS-25]) scores were collected from seven administrative areas of Japan. Results The reference values of the three test scores were generated and all three test scores gradually decreased among young-to-middle-aged individuals and rapidly decreased in individuals aged over 60 years. The stand-up test score began decreasing significantly from the age of 30 years. The trajectories of decrease in the two-step test score with age was slightly different between men and women especially among the middle-aged individuals. The two physical test scores were more sensitive to aging than the self-reported test score. Conclusion The reference values generated in this study could be employed to determine whether an individual has mobility comparable to independent community dwellers of the same age and sex.

A silicon epitaxial growth process in a trichlorosilane-hydrogen system was evaluated using a quartz crystal microbalance (QCM) placed at the exhaust of a chemical vapor deposition reactor designed for the Minimal Fab. The QCM showed two types of the frequency decrease behaviors, that is, i) a quick shift due to the gas property change caused by the trichlorosilane gas introduction into the ambient hydrogen and ii) the continuous and gradual decrease due to the byproduct deposition on the QCM surface during the silicon epitaxial growth. Because both i) and ii) showed a relationship with the silicon epitaxial growth rate, the in-situ information obtained by the QCM was expected for the real time monitoring of the film deposition process.

Effective process conditions to utilize a slim vertical silicon chemical vapour deposition reactor were studied. Based on a numerical analysis taking into account the gas flow, heat and species transport, particularly over a wide range of the trichlorosilane gas concentrations from 1% to 40% in ambient hydrogen, a heavy and cold gas was shown to quickly go downward to the hot wafer surface through the slim vertical gas channel. The gas phase near the wafer was sufficiently cooled to produce a cold wall thermal condition which enabled the trichlorosilane gas consumption only at the wafer surface, even in a non-axisymmetric and non-steady condition. The slow wafer rotation, less than 30 rpm, had a considerable effect, such as that increasing the gas phase temperature gradient for suppressing the gas phase reaction.

Study Design: Retrospective cross-sectional study. Purpose: To investigate the relationship between ligamentum flavum (LF) hypertrophy and lumbar segmental motion. Overview of Literature: The pathogenesis of LF thickening is unclear and whether the thickening results from tissue hypertrophy or buckling remains controversial. Methods: 296 consecutive patients underwent assessment of the lumbar spine by radiographic and magnetic resonance imaging (MRI). Of these patients, 39 with normal L4–L5 disc height were selected to exclude LF buckling as one component of LF hypertrophy. The study group included 27 men and 12 women, with an average age of 61.2 years (range, 23–81 years). Disc degeneration and LF thickness were quantified on MRI. Lumbar segmental spine instability and presence of a vacuum phenomenon were identified on ra diographic images. Results: The distribution of disc degeneration and LF thickness included grade II degeneration in 4 patients, with a mean LF thickness of 2.43±0.20 mm; grade III in 10 patients, 3.01±0.41 mm; and grade IV in 25 patients, 4.16±1.12 mm. LF thickness significantly increased with grade of disc degeneration and was significantly correlated with age ( r =0.55, p

Background Delay in fracture healing or non-union can be devastating complication. Recent studies have reported that teriparatide (TP) demonstrated effectively on callus formation and mechanical strength and zoledronate (ZA) increased the callus size and resistance at the fracture site in rat fracture model. In this study, the effects of combination therapy with low dose TP and ZA on fracture healing was evaluated. Methods From 1 week post-operation, TP (5 times a week administration) and ZA (0.1 mg/kg single administration) were administered by dividing the rats into the following five groups: TP 1 μg group {T(1): TP 1 μg/kg}, ZA group (ZA:0.1 mg/kg), TP1 μg+ZA group {T(1)+ZA: TP 1 μg/kg+ZA}, TP 10 μg+ZA group {T(10)+ZA: TP 10 μg/kg + ZA}, and control group (C: administered saline). Rt femurs were excised 7 weeks after the surgery; bone fusions were evaluated with soft X-ray images on a 4-point scale. And the histopathological examination was performed in demineralized and non-demineralized specimens. Furthermore, the Radiographic Union Scale was conducted in all specimens. Results About the bone fusions rates, C, T(1), ZA, T(1)+ZA, and T(10)+ZA groups demonstrated 20.0%, 55.6%, 70.0%, 70.0%, and 80.0%, respectively, and with 4-point scale, each group was 0.50, 1.56, 2.00, 2.60, and 2.80 points, respectively. The callus volume was significantly increased to 16.66 mm2 and 17.75 mm2 in the T(1)+ZA and T(10)+ZA groups, respectively, while 10.65 mm2 (p

We attempted to enhance the antitumor effects of tumor lysate-pulsed dendritic cells by eliminating regulatory T cells. The combinatorial effects of dendritic cells and agonist anti-glucocorticoid-induced tumor necrosis factor receptor (anti-GITR) antibodies were investigated with respect to enhancement of the systemic immune response, elimination of regulatory T cells, and inhibition of tumor growth. To determine whether the combination of dendritic cells and anti‑GITR antibodies could enhance systemic immune responses and inhibit primary tumor growth in a murine osteosarcoma (LM8) model. We established the following 4 groups of C3H mice (20 mice in total): i), control IgG-treated mice; ii), tumor lysate-pulsed dendritic cell‑treated mice; iii), agonist anti-GITR antibody-treated mice; and iv), agonist anti-GITR antibody- and tumor lysate-pulsed dendritic cell‑treated mice.The mice that received the agonist anti-GITR antibodies and tumor lysate-pulsed dendritic cells displayed inhibited primary growth, prolonged life time, reduced numbers of regulatory T lymphocytes in the spleen, elevated serum interferon-γ levels, increased number of CD8+ T lymphocytes. The mice that received combined therapy had reduced level of immunosuppressive cytokines in tumor tissue and serum. Combining agonist anti-GITR antibodies with tumor lysate-pulsed dendritic cells enhanced the systemic immune response. These findings provide further support for the continued development of agonist anti-GITR antibodies as an immunotherapeutic strategy for osteosarcoma. We suggest that our proposed immunotherapy could be developed further to improve osteosarcoma treatment.

Chlorosilane gas transport in ambient hydrogen in a slim vertical cold wall chemical vapor deposition reactor was real-time monitored using a quartz crystal microbalance (QCM) using its behaviour responding to the properties of the gas mixture. The QCM frequency quickly decreased by introducing the trichlorosilane gas, while it slowly decreased by the dichlorosilane gas. The QCM frequency behavior was explained by the gas flow condition, such as the plug flow and recirculating flow, in the reactor. The relationship was consistent with the gas flow calculations, because the heavy and light gases could directly flow downward and recirculate, respectively, in the chamber due to natural convection. The information obtained from the QCM frequency behavior is expected to be utilized for the real-time gas monitoring and for the process design.

A chemical vapor deposition reactor for producing thin silicon films was designed and developed for achieving a new electronic device production system, the Minimal Manufacturing, using a half-inch wafer. This system requires a rapid process by a small footprint reactor. This was designed and verified by employing the technical issues, such as (i) vertical gas flow, (ii) thermal operation using a highly concentrated infrared flux, and (iii) reactor cleaning by chlorine trifluoride gas. The combination of (i) and (ii) could achieve a low heating power and a fast cooling designed by the heat balance of the small wafer placed at a position outside of the reflector. The cleaning process could be rapid by (iii). The heating step could be skipped because chlorine trifluoride gas was reactive at any temperature higher than room temperature.

The effects of dendritic cells (DCs) with low dose doxorubicin on the enhancement of the systemic immune response, including the effects on calreticulin (CRT) expression, heat shock protein 70 (HSP70) on the cell surface expression, and the enhancement of high mobility group box 1 (HMGB1) release from cancer cells, remain unclear. The present study investigated whether the combination of DCs and doxorubicin (ADM) induces immune cell death, and leads to tumor growth inhibition in a murine osteosarcoma model. To evaluate immune response activation in vivo, 4 groups of mice were established: i) untreated mice, ii) DC-treated mice, iii) ADM-treated mice, and iv) DC and ADM-treated mice. Immunological cell death and CRT, HSP70, and HMGB1 expression levels were higher in doxorubicin-treated cells than those in untreated or those treated with DCs alone. NF-κB expression was higher in the DCs after ligand activation using CRT, HSP70, or HMGB1 in vitro. Mice treated with DCs and ADM displayed an increased number of CD8+ T-lymphocytes within metastatic tumors and inhibition of metastatic growth. The expression of CRT and the release of HMGB1 from tumor tissues were increased in the ADM-treated groups. Treatment with DCs and ADM resulted in the highest serum interferon-γ levels. Combining ADM, which can induce immunogenic cell death, with DCs enhanced the systemic immune response. The findings of the present study provide further support for the continued development of antitumor agents that induce cell death and the immune response to target osteosarcoma.

Short non-coding RNAs, called microRNAs (miRNAs), regulate cell biology by affecting the expression of target genes. However, we know little about the miRNAs regulating the growth and progression of Ewing's sarcoma (ES). To identify possible oncogenic factors in ES, we used a microarray-based approach to profile the changes in the expression of miRNAs and the downstream mRNAs in five ES cell lines. One miRNA, miR‑138, was significantly downregulated, whereas the expression of focal adhesion kinase (FAK) was significantly upregulated in all tested ES cells. When miR‑138 was transfected into ES cell lines, the expression of FAK in these cells was greatly suppressed and inhibited the proliferation and mobility of ES cells. Overexpression of miR‑138 in vitro resulted in further inhibition of the cell cycle at the G1 phase and in the induction of anoikis, in a dose- and time-dependent manner. Moreover, miR‑138 overexpression in ES cells significantly suppressed the number of distant metastases in vivo. The data in the present study demonstrates for the first time a novel mechanism that regulates the expression of FAK via miR‑138 in ES cells.

Purpose.To discuss the indications and therapeutic outcomes of synovectomy, debridement, and continuous irrigation for the treatment of pyogenic arthritis caused by intra-articular injection used in the treatment of osteoarthritis of the knee.Methods.Records of 41 patients with infectious arthritis of the knee who presented to our hospital from 1981 were reviewed. 11 of them had a history of intra-articular injection. They underwent synovectomy, debridement, and continuous irrigation using a Salem double-lumen tube after confirmation that one side of the femorotibial joint cartilage was basically healthy.Results.The infection was successfully treated in 9 of the 11 patients. Of these 9 patients, one died after 3 years and 2 underwent total knee arthroplasty after 3 and 8 years. The remaining 6 patients were followed up for 5 to 15 years. Five of them had deteriorating arthropathy, and the condition was unchanged in the others. Two of these 6 patients had pain while walking, and their Japanese Orthopaedic Association scores were 70. The remaining 4 had good knee function and reduction of pain, with a mean Japanese Orthopaedic Association score of 91 and a mean range of motion of 131 degrees.Conclusion.Arthrodesis is frequently considered the treatment for osteoarthritis if the joint destruction has affected the weight-bearing surface. However, in our experience, even when inflammatory granulation develops in the cartilage surface of one side of the femorotibial joint, good results can still be obtained by synovectomy, debridement, and continuous irrigation. After the pyogenic arthritis has subsided, if osteoarthritis has advanced and bowleg has exacerbated, further treatment options are available, such as tibial resection and even joint replacement. Continuous irrigation should be considered a feasible treatment option for pyogenic arthritis.

For young patients who have early signs of coxarthrosis resulting from acetabular dysplasia, periace- tabular osteotomies for correcting abnormal stress distribu- tion can be useful for preventing the progression of the disease. However, it is difficult to confirm the optimal transpo- sition of the osteotomized acetabular fragment. To deal with this problem, we devised a computer program to support preoperative planning. Hip images obtained by computed tomography were loaded into our program, and a three- dimensional voxel model was created. Then, osteotomy was simulated and the pressure distribution was analyzed with a rigid-body spring analysis (computational nonlinear mechani- cal analysis). The three-dimensional pressure distributions in seven dysplastic hips were evaluated before and after virtual rotational acetabular osteotomy. A peak pressure was calcu- lated for every 5° of rotation of the acetabular fragment. The peak pressure decreased gradually and increased again after- ward, indicating the optimal transposition of the acetabular fragment. The postoperative peak pressure decreased to about 40% in the most improved case. This program allows the hip joint mechanics to be evaluated easily so that the advantages and disadvantages of various surgical methods can be examined biomechanically prior to surgery.

Since 1990, a total of ten joints in nine patients with infected total knee arthroplasty have been treated in our department within 21 days of the onset of infection. Their radiographs showed no evidence of implant loosening or "moth-eaten" appearance. They underwent synovectomy, debridement, and continuous irrigation without implant removal. Continuous irrigation was maintained for 7-29 days. It was possible to retain implants in eight joints of seven patients. Two joints of two patients were removed. Pain disappeared in all eight joints in which the implants were retained. Four patients could walk with one cane; one patient could walk with one crutch. Range of motion in five joints remained over 100 degrees. We recommend synovectomy, debridement, and continuous irrigation to cure an early stage infection of total knee arthroplasty.

We report on the crystallographic structure of the layered perovskite iridate Sr3Ir2O7, investigated using transmission electron microscopy. The space group was found to be Bbcb ( D 2 h 22 , No. 68 in the International Tables for Crystallography) at 315 K. A very fine twin structure with 90° rotation with respect to the c-axis was observed. The crystal structure at temperatures lower than 285 K, where a phase transition from paramagnetism to weak ferromagnetism is known to occur, was also examined. There was no difference in the extinction rule for the diffraction patterns between the two phases. We conclude that there is no change in the space group for this magnetic transition. There still remains the possibility of a change in the rotation angle of IrO6 octahedrons and a corresponding change in the interatomic distance between Ir and O, though.

We report a uniaxial pressure-dependence of magnetism in layered perovskite strontium ruthenate Sr3Ru2O7. By applying a relatively small uniaxial pressure, greater than 0.1 GPa normal to the RuO2 layer, ferromagnetic ordering manifests below 80 K from the enhanced-paramagnet. Magnetization at 1 kOe and 2 K becomes 100 times larger than that under ambient condition. Uniaxial pressure dependence of Curie temperature T_C suggests the first order magnetic transition. Origin of this uniaxial-pressure induced ferromagnetism is discussed in terms of the rotation of RuO6 octahedra within the RuO2 plane., 8 pages, 3 figures. to be published in Journal of the Physical Society of Japan, vol.73, No.5 (2004)

A case of spinal cord injury in a 16-year-old girl that was caused by stab wound is reported. She was admitted to the emergency department one day after being stabbed. When admitted she was conscious but was experiencing weakness in the lower limbs. The knife had penetrated through the left lamina to the right vertebral body at Th8. Treatment was conservative, and very good functional recovery was achieved.

We have investigated the thermal expansion of the ferrimagnet FeSe of the hexagonal system by synchrotron radiation powder X-ray diffraction from room temperature down to 90 K. The lattice constants show anisotropic change against temperature. Especially, the c-axis expands down to 170 K, exhibiting negative linear thermal expansion. Almost the same behavior is found in the temperature dependence of the magnetization. This implies that the anomalous change of the c-axis has a strong correlation with magnetism. Magnetic fields up to 0.4 T do not affect the lattice constants at room temperature. Electrical resistivity indicates metallic behavior, i.e., there is a finite density of the state at the Fermi energy, consisting of the Fe3d and the Se4p states.

Aims/Introduction: Accumulation of intramyocellular lipid (IMCL) is associated with insulin resistance. However, the factors affecting the change in IMCL remain to be elucidated. The aim of the present study was to determine the factors that influence the change in IMCL level after high‐fat loading. Materials and Methods: The study subjects were 37 non‐obese men. Each subject consumed a high‐fat diet for 3 days after a normal‐fat diet for 3 days. After each diet program, IMCL levels in the tibialis anterior (TA‐IMCL) and soleus (SOL‐IMCL) were measured by proton magnetic resonance spectroscopy. Glucose infusion rate (GIR) was evaluated by euglycemic hyperinsulinemic clamp as an index of peripheral insulin sensitivity. Results: The high‐fat diet significantly increased TA‐IMCL and SOL‐IMCL by ∼30 and ∼20%, respectively (P

The concept of quantum criticality is proving to be central to attempts to understand the physics of strongly correlated electrons. Here, we argue that observations on the itinerant metamagnet Sr 3 Ru 2 O 7 represent good evidence for a new class of quantum critical point, arising when the critical end point terminating a line of first-order transitions is depressed toward zero temperature. This is of interest both in its own right and because of the convenience of having a quantum critical point for which the tuning parameter is the magnetic field. The relationship between the resultant critical fluctuations and novel behavior very near the critical field is discussed.

We report the results of low temperature transport, specific heat, and magnetization measurements on high quality single crystals of the bilayer perovskite ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$, which is a close relative of the unconventional superconductor ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$. Metamagnetism is observed, and transport and thermodynamic evidence for associated critical fluctuations is presented. These relatively unusual fluctuations might be pictured as variations in the Fermi surface topography itself.

It is said that early diagnosis is important in spinal infection, and MRI is useful for such diagnoses, because the disease often progresses rapidly, with late diagnosis leading to large epidural abscess and palsy.We report a 75-year-old man who had vertebral osteomyelitis (Th8-9) with diffuse epidural abscess compressing the Th6-9 region. Because he had dimentia, and was in a septic shock state, we managed only laminectomy and debridement by the posterior approach, after which irrigation was performed. The infection was difficult to control with antibiotics, and he died of multiple organ failure after six months.

We show that single-crystalline ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$ grown by a floating-zone technique is an isotropic paramagnet and a quasi-two-dimensional metal, as spin-triplet superconducting ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ is. The ground state is a Fermi liquid with very low residual resistivity $(\ensuremath{\approx}3 \ensuremath{\mu}\ensuremath{\Omega}\mathrm{cm}$ for in-plane currents) and a nearly ferromagnetic metal with the largest Wilson ratio ${R}_{\mathrm{W}}g~10$ among paramagnets so far. This contrasts with the ferromagnetic order at ${T}_{\mathrm{c}}=104 \mathrm{K}$ reported on single crystals grown by a flux method [Cao et al., Phys. Rev. B 55, R672 (1997)]. However, we have found a dramatic changeover from paramagnetism to ferromagnetism under applied pressure. This suggests the existence of a substantial ferromagnetic instability in the Fermi-liquid state.

It is well known that hydroxyapatite is a useful biomaterial with biocompatibility and nontoxicity in the reconstructive field of orthopedic surgery.We report a case with suspected pes anserinus bursitis or enthesopathy caused by hydroxyapatite. A 56-year-old woman suffering from renal sarcoidosis with bone defect of the left medial tibial condyle underwent operation for hydroxyapatite 3 years ago. At this time, though the hydroxyapatite spilt and fell in the operation field, no symptoms were seen for 3 years.Because of recurring sharp pain in the same area, we thought that this pain was caused by hydroxyapatite, and we removed the hydroxyapatite, after which the sharp pain disappeared.Histologically, foreign body gaint cells around the hydroxyapatite particle were observed, but no inflammatory reaction and calcification were seen.

We have prepared rare earth oxysulfides (PrO)CuS and (NdO)CuS in order to introduce magnetic moments into the non-magnetic p-type semiconductor (LaO)CuS. Both compounds are semiconductors with high electrical resistivity, and show the paramagnetic behavior. The temperature dependence of the magnetic susceptibility is well explained by the trivalent rare earth ion. However, it deviates from simple Curie Wiess law below 100 K due to the crystal field effect on rare earth ions. We have succeeded to reproduce their magnetic properties by the calculation taking the crystal field effect into account using the operator equivalent method.

Non-cuprate layered perovskite Sr2RuO4, which is an analogue of (La,Sr)2CuO4, exhibits superconductivity below Tc≈1K. We have synthesized a new system Sr3−xCaxRu2Oy and found the solubility of Ca to be at least as much as x = 2. These samples are not superconductive down to 2K but magnetically ordered. The x dependence of the lattice parameters and that of Tmag clearly indicate that there are at least two distinct structural phases in Sr3−xCaxRu2Oy.

We describe powder and single-crystal inelastic neutron scattering experiments on a spinel-type antiferromagnet GeCo${}_{2}$O${}_{4}$, represented by an effective total angular momentum ${J}_{\mathrm{eff}}=1/2$. Several types of nondispersive short-range magnetic excitations were discovered. The scattering intensity maps in $\mathbit{Q}$ space are well reproduced by dynamical structure factor analyses using molecular model Hamiltonians. The results of analyses suggest that the molecular excitations below ${T}_{N}$ arise from molecular ground states, one of which consists of antiferromagnetically coupled ferromagnetic subunits. The quasielastic excitations above ${T}_{N}$ are interpreted as its precursor. A combination of frustration and ${J}_{\mathrm{eff}}=1/2$ might induce these quantum phenomena.

Ultrasound velocity measurements of the orbitally-frustrated GeCo$_2$O$_4$ reveal unusual elastic instabilities due to the phonon-spin coupling within the antiferromagnetic phase. Shear moduli exhibit anomalies arising from the coupling to short-range ferromagnetic excitations. Diplike anomalies in the magnetic-field dependence of elastic moduli reveal magnetic-field-induced orbital order-order transitions. These results strongly suggest the presence of geometrical orbital frustration which causes novel orbital phenomena within the antiferromagnetic phase.

We report single-crystal neutron diffraction studies on a spinel antiferromagnet GeCo$_2$O$_4$, which exhibits magnetic order with a trigonal propagation vector and tetragonal lattice expansion ($c/a\simeq1.001$) below $T_{\rm N}=21$ K. For this inconsistency between spin and lattice in symmetry, magnetic Bragg reflections with a tetragonal propagation vector were discovered below $T_{\rm N}$. We discuss spin and orbital states of Co$^{2+}$ ion underlying the new magnetic component., Comment: 3 pages 2 figures, submitted to ICFCM proceeding (Journal of Physics: Conference Series, 2011)

We have investigated the electronic structures of recently discovered superconductor FeSe by soft-x-ray and hard-x-ray photoemission spectroscopy with high bulk sensitivity. The large Fe 3d spectral weight is located in the vicinity of the Fermi level (EF), which is demonstrated to be a coherent quasi-particle peak. Compared with the results of the band structure calculation with local-density approximation, Fe 3d band narrowing and the energy shift of the band toward EF are found, suggesting an importance of the electron correlation effect in FeSe. The self energy correction provides the larger mass enhancement value (Z^-1=3.6) than in Fe-As superconductors and enables us to separate a incoherent part from the spectrum. These features are quite consistent with the results of recent dynamical mean-field calculations, in which the incoherent part is attributed to the lower Hubbard band., Comment: 8 pages, 5 figures, 1 talble

Ultrasound velocity measurements of cubic spinel ${\text{GeCo}}_{2}{\text{O}}_{4}$ in single crystal were performed for the investigation of shear and compression moduli. The shear moduli in the paramagnetic state reveal the absence of Jahn-Teller activity despite the presence of orbital degeneracy in the ${\text{Co}}^{2+}$ ions. Such a Jahn-Teller inactivity indicates that the intersite orbital-orbital interaction is much stronger than the Jahn-Teller coupling. The compression moduli in the paramagnetic state near the N\'eel temperature ${T}_{N}$ reveal that the most relevant exchange path for the antiferromagnetic transition lies in the [111] direction. This exchange-path anisotropy is consistent with the antiferromagnetic structure with the wave vector $q\ensuremath{\parallel}[111]$, suggesting the presence of bond frustration due to competition among a direct ferromagnetic interaction and several distant-neighbor antiferromagnetic interactions. In the Jahn-Teller-inactive condition, the bond frustration can be induced by geometrical orbital frustration of ${t}_{2g}\text{\ensuremath{-}}{t}_{2g}$ interaction between the ${\text{Co}}^{2+}$ ions, which can be realized in the pyrochlore lattice of the high-spin ${\text{Co}}^{2+}$ with ${t}_{2g}$-orbital degeneracy. In ${\text{GeCo}}_{2}{\text{O}}_{4}$, the tetragonal elongation below ${T}_{N}$ releases the orbital frustration by quenching the orbital degeneracy.

The local spectroscopic signatures of metamagnetic criticality in Sr(3)Ru(2)O(7) were explored using scanning tunneling microscopy (STM). Singular features in the tunneling spectrum were found close to the Fermi level, as would be expected in a Stoner picture of itinerant electron metamagnetism. These features showed a pronounced magnetic field dependence across the metamagnetic critical point, which cannot be understood in terms of a naive Stoner theory. In addition, a pseudogap structure was observed over several tens of meV, accompanied by a c(2 x 2) superstructure in STM images. This result represents a new electronic ordering at the surface in the absence of any measurable surface reconstruction.