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Here we report the magnetic properties of the layered cobalt oxide system, Li x CoO 2 , in the whole range of Li composition, 0 Յ x Յ 1. Based on dc-magnetic-susceptibility data, combined with results of 59 Co nuclear magnetic resonance ͑NMR͒ and nuclear quadrupole resonance ͑NQR͒ observations, the electronic phase diagram of Li x CoO 2 has been established. As in the related material Na x CoO 2 , a magnetic critical point is found to exist between x = 0.35 and 0.40, which separates the Pauli-paramagnetic and Curie-Weiss metals. In the Pauli-paramagnetic regime ͑x Յ 0.35͒, the antiferromagnetic spin correlations systematically increase with decreasing x. Nevertheless, CoO 2 , the x = 0 end member is a noncorrelated metal in the whole temperature range studied. In the Curie-Weiss regime ͑x Ն 0.40͒, on the other hand, various phase transitions are observed. For x = 0.40, a susceptibility hump is seen at 30 K, suggesting the onset of static antiferromagnetic order. A magnetic jump, which is likely to be triggered by charge ordering, is clearly observed at T t Ϸ 175 K in samples with x = 0.50 ͑=1 / 2͒ and 0.67 ͑=2 / 3͒, while only a tiny kink appears at T Ϸ 210 K in the sample with an intermediate Li composition, x = 0.60. Thus, the phase diagram of the Li x CoO 2 system is complex and the electronic properties are sensitively influenced by the Li content ͑x͒.

Thermoelectric properties of the layered cobalt oxide system Li x CoO 2 were investigated in a wide range of Li compositions, 0.98 x 0.35. Single-phase bulk samples of Li x CoO 2 were successfully obtained through electrochemical deintercalation of Li from the pristine LiCoO 2 phase. While Li x CoO 2 with x 0.94 is semiconductive, the highly Li-deficient phase (0.75 x 0.35) exhibits metallic conductivity. The magnitude of the Seebeck coefficient at 293 K (S 293K ) significantly depends on the Li content (x). The S 293K value is as large as +70 up to +100 μV/K for x 0.94, and it rapidly decreases from +90 μV/K to +10 μV/K as x is lowered within a Li composition range of 0.75 x 0.50. This behavior is in sharp contrast to the results of x 0.40 for which the S 293K value is small and independent of x (+10 μV/K), indicating that a discontinuous change in the thermoelectric characteristics takes place at x = 0.40-0.50. The unusually large Seebeck coefficient and metallic conductivity are found to coexist in a narrow range of Li composition at about x = 0.75. The coexistence, which leads to an enhanced thermoelectric power factor, may be attributed to unusual electronic structure of the two-dimensional CoO 2 block.

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We present the general properties of multihadron final states produced by e + e annihilation at center-of-mass energies from 52 to 57 GeV in the AMY detector at the KEK collider TRISTAN. Global shape, inclusive charged-particle, and particle-flow distributions are presented. Our measurements are compared with QCDS-fragmentation models that use either leading-logarithmic parton-shower evolution or QCD matrix elements at the parton level, and either string or cluster fragmentation for hadronization.

A new video-speed current-mode CMOS sampleand-hold IC has been developed. It operates with a supply voltage as low as 1.5 V, a signal-to-noise ratio ( ) of 57 dB and 54 dB with a 1-MHz input signal at clock frequencies of 20 and 30 MHz, and a power dissipation of 2.3 mW. It consists of current-mirror circuits with the node voltages at the input and the output terminals which are kept constant in all phases of the input signal by the use of low-voltage operational amplifiers; this reduces the signal current dependency. The low-voltage operational amplifier consists of a MOS transistor and a constant current source in a common-gate amplifier configuration. Only two analog switches in differential form were used to construct the differential sample-and-hold circuit. This minimizes the error caused by the switch feedthrough, and thus high accuracy can be realized. Since there is no analog switch in the input path, it is possible to convert the input signal voltage to a current by simply connecting an external resistor. The circuit was fabricated using standard 0.6m MOS devices with normal threshold voltages ( th ) of +0.7 V (nMOS) and 0.7 V (pMOS).

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Electrical characteristics associated with radiation detection were measured on single-crystal natural type-IIa diamond using two techniques: charged particle-induced conductivity and time-resolved transient photoinduced conductivity. The two techniques complement each other: The charged particle-induced conductivity technique measures the product of the carrier mobility μ and lifetime τ throughout the bulk of the material while the transient photoconductivity technique measures the carrier mobility and lifetime independently at the first few micrometers of the material surface. For each technique, the μτ product was determined by integration of the respective signals. The collection distance that a free carrier drifts in an electric field was extracted by each technique. As a result, a direct comparison of bulk and surface electrical properties was performed. The data from these two techniques are in agreement, indicating no difference in the electrical properties between the bulk and the surface of the material. The collection distance continues to increase with field up to 25 kV/cm without saturation. Using the transient photoconductivity technique the carrier mobility was measured separately and compared with a simple electron-phonon scattering model. The general characteristics of carrier mobility, lifetime, and collection distance at low electric field appear to be adequately described by the model.