Low temperature and high pressure techniques are shown to be very useful tools for the study of solid state physics. We review some interesting topics related to the fundamental physics in solid state physics, focusing on insulator-metal transition, spin and charge density wave, the Kondo insulator, and others. We describe how efficiently modern observation techniques and theories were combined with high pressure and low temperature to gain insight into the properties of solids which were hindered at elevated temperatures and at normal pressure.
Magnetism is an important character in various interesting physical properties. Pressure is one of the most important physical parameters. In this paper, piston cylinder type high-pressure apparatuses and cell materials for magnetization measurements are reviewed. Furthermore some experimental results are given briefly.
We have succeeded in developing a new high-pressure cell designed for measuring the absolute value of the electrical resistivity or AC susceptibility in magnetic fields at low temperatures. This pressure cell, based on a technique using modified Bridgman anvils with a Teflon capsule, can generate nearly hydrostatic pressure at least up to 6.0 GPa. The most important feature of this pressure cell is its compact body such that it can be attached to a dilution refrigerator in a superconducting magnet. One of its applications is for measurements under multi-extreme conditions, which is demonstrated by the investigation into the pressur-induced superconducting state of spin-ladder Sr14-xCaxCu24O41 single crystals.
Recent developments of DAC (diamond anvil cell) experiments at low temperatures are briefly reviewed. Magnetic susceptibility measurements have been improved and the SQUID system is applied to the DAC measurements. Electrical resistivity measurements in the DAC are also reviewed. A DAC is a powerful tool in the investigation of superconductors and magnetic materials.
Neutron scattering is powerful tool for studying magnetism from the microscopic point of view. In this article, experimental techniques of high-pressure neutron scattering with the sapphire anvil cell (SAC) are described. Maximum pressure generated by the SAC with 2.5 mm anvil tip and Cu gasket is about 6 GPa at present. Magnetic structures of CeSb are investigated up to 4.6 GPa with the SAC. The neutron focusing device with super mirror, which is useful for the experiments with tiny sample is also shown.
In this article, we review recent activities at BL02B1 at SPring-8 in the field of single-crystal and high-pressure X-ray diffraction experiments. A comparison of experiments performed two decades ago with the new frontier experiments is also shown. Special attention is paid to the importance of the quantitative arguments. The chracteristics of the single-crystal and high-pressure experiments are also compared with the powder-sample and high-pressure experiments.
High pressure chemistry is now recognized as a powerful method to achieve synthetic organic reactions which are not readily accessible by usual means. This article deals with the recent developments made in this laboratory such as 1) epoxide ring-opening reactions, 2) Michael addition reaction, 3) nucleophilic aromatic substitution, and 4) several condensation reactions. The application of this technique to natural product synthesis, asymmetric synthesis, and the molecular design of new functional materials is also discussed.
Pressure effects upon asymmetric photochemical reactions are discussed in the context of entropy control of these reactions. In the enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to chiral (E)-isomer (1E) sensitized by chiral aromatic esters (2-7), the 1E/1Z ratio and the enantiomeric excess (ee) of 1E are critical finctions of the applied pressure, accompanying an unprecedented switching of the product chirality. Furthermore the differential activation parameters (ΔΔH‡, ΔΔS‡ and ΔΔV‡) obtained by changing pressure and temperature cleary indicate that these variants act as independent factors in the enantiodifferentiating process. This opens a new channel to the multidimensional control of not only asymmetric photochemical but also conventional thermo/photo/biochemical reactions in which weak interactions are the principal driving force or determining factor.
The effects of temperature and pressure on the structural formations in a ternary microemulsion system were reviewed. From the static measurement by means of a small angle x-ray and neutron scattering, similar phase transitions with increasing temperature or pressure were observed. Introducing a normalized temperature and pressure, the similarity and dissimilarity of those two phase transitions were clarified. From the dynamic measurement utilizing neutron spin echo, it was demonstrated that the membrane dynamics at the high-pressure phase were completely different from the high temperature phase. These differences suggest differing mechanisms for the pressure-induced phase transition and the temperature-induced transition.