Synchrotron X-ray Magnetic Scattering Studies under Strong Magnetic Fields

点击翻译按钮获取中文摘要

In this project, we aim at clarifying the magnetic and structural changes in quantum magnetic systems under high magnetic fields using synchrotron X-ray diffraction technique. Some of the outstanding findings obtained from this project are briefly described below.(1)We have found that the incommensurability in the high field phase of a spin-Peierls compound, CuGeO_3 depends much on temperature near the critical field (〓12 T), while at high enough field it is independent of temperature. We have interpreted that this finding is due to a stabilization of the incommensurate state by a strong magnetic field which suppresses thermal fluctuations.(2)At the critical field from the spin liquid to a long-range ordered phase of a spin 1/2 ladder compound Cu_2(C_5H_<12>N_2)_2Cl_4,one expects a generalized spin-Peierls transition, in which a lattice distortion is predicted to occur. We have performed X-ray diffraction study on a single crystal of this compound at the World's lowest temperature of 0.04 K and at high fields. We have found that the lattice constant along the a-axis shows a discontinuous change at the critical field.(3)Synchrotron X-ray diffraction measurements have been performed on CeP which is a typical example of dense Kondo systems despite its small carrier concentration. In CeP two layers of Γ_8 like Ce and a layer of Γ_7 like Ce are stacked with a period which changes with an applied magnetic field. From our study performed in high fields up to 14 T we have discovered new phases with 8 and 9 periods.(4)We are successful in developing a pulsed high field for synchrotron X-ray diffraction. We have constructed a split pair magnet capable of producing pulsed field up to 35 T without destruction and measured X-ray diffraction on some compounds.