Metal-insulator transition in vanadium dioxide nanobeams: probing sub-domain properties of strongly correlated materials

Many strongly correlated electronic materials, including high-temperature superconductors, colossal magnetoresistance and metal-insulator-transition (MIT) materials, are inhomogeneous on a microscopic scale as a result of domain structure or compositional variations. An important potential advantage of nanoscale samples is that they exhibit the homogeneous properties, which can differ greatly from those of the bulk. We demonstrate this principle using vanadium dioxide, which has domain structure associated with its dramatic MIT at 68 degrees C. Our studies of single-domain vanadium dioxide nanobeams reveal new aspects of this famous MIT, including supercooling of the metallic phase by 50 degrees C; an activation energy in the insulating phase consistent with the optical gap; and a connection between the transition and the equilibrium carrier density in the insulating phase. Our devices also provide a nanomechanical method of determining the transition temperature, enable measurements on individual metal-insulator interphase walls, and allow general investigations of a phase transition in quasi-one-dimensional geometry.Comment: 9 pages, 3 figures, original submitted in June 200

Orbital order in the low-dimensional quantum spin system TiOCl probed by ESR

We present electron spin resonance data of Ti$^{3+}$ (3$d^1$) ions in single crystals of the novel layered quantum spin magnet TiOCl. The analysis of the g tensor yields direct evidence that the d_{xy} orbital from the t_{2g} set is predominantly occupied and owing to the occurrence of orbital order a linear spin chain forms along the crystallographic b axis. This result corroborates recent theoretical LDA+U calculations of the band structure. The temperature dependence of the parameters of the resonance signal suggests a strong coupling between spin and lattice degrees of freedom and gives evidence for a transition to a nonmagnetic ground state at 67 K.Comment: revised version, accepted for publication in Phys. Rev. B, Rapid Com

Pressure induced high-spin to low-spin transition in FeS evidenced by x-ray emission spectroscopy

We report the observation of the pressure-induced high-spin to low-spin transition in FeS using new high-pressure synchrotron x-ray emission spectroscopy techniques. The transition is evidenced by the disappearance of the low-energy satellite in the Fe K$\beta$ emission spectrum of FeS. Moreover, the phase transition is reversible and closely related to the structural phase transition from a manganese phosphide-like phase to a monoclinic phase. The study opens new opportunities for investigating the electronic properties of materials under pressure.Comment: ReVTeX, 4 pages, 3 figures inserted with epsfig. minor modifications before submission to PR

Sugar Scrub Effects on Skin Barrier Function and Heat Retention in Low Birth Weight Infants

Objective: This investigation sought to compare changes in body heat after using a sugar scrub to bathe lowbirth weight infants (< 2,500 g), compared with those bathed using conventional baby soap, and to evaluatethe relationship between skin barrier function and changes in body heat.Design: Non-Randomized clinical trialsSetting: A neonatal intensive care unit in a university hospital in JapanParticipants: 22 Low birth weight infants for whom bathing was permittedMethods: Sebum quantity and skin temperature were each measured before and after bathing for a control groupbathed with conventional baby soap and a group bathed with a sugar scrub skin care product. Ethical approvalfor this study was obtained from Aino university of Ethics committee review board (Approval number/27)Results: The results demonstrated that both sebum quantity and skin temperature increased significantly afterbathing in the sugar scrub group compared with the baby soap group.Conclusion: Increases in sebum quantity are thought to influence the normal barrier function of skin and to helpretain skin temperature. This study suggests that the use of this skin care product can be expected to effectivelyhelp maintain body temperature in low birth weight infants, who are prone to low body temperature

チョウイオン ドウデンタイ α-AGIガタ ノ ソウテンイ ニオケル ヒカリ オンキョウ スペクトル 2

The photoacoustic (PA) signal of AgI has been measured as a funcion of temperature from 24℃ to 180℃ and chopping frequencies of excitation light from 4 to 50 Hz. The magnitude of PA signal excited with photon energy beyond the band gap decreases down to one-third as increasing temperature from 24℃ to 180℃, and similar decrease in magnitude of PA signal down to one-fifth has been observed as increasing chopping frequency from 4 to 50 Hz. The observed change in magnitude of PA signal at first-order phase transitions is larger than the expectation from RG theory. This curious feature might be understood by the frequency dependence of heat capacity