Zeeman modulated spin echo in orthorhombic symmetry

Article

关键词: HYPERFINE FIELDS;    PSEUDOGAP STATE;    MAGNETIC ORDER;    BA SITE;    SUPERCONDUCTOR;   

DOI  :  10.1103/PhysRevB.89.235108

来源: SCIE

【 摘 要 】

The experimental study of the modulation of the envelope of spin-echo signals due to internal and external fields is an important spectroscopic tool to detect very small internalmagnetic fields. We derive the free induction decay and the frequency spectrum and amplitude of spin-echo signals for arbitrary orientation of fields with respect to crystalline axis for nuclei in a crystal of orthorhombic symmetry. Results reproduce the results that no modulation should be observed in tetragonal crystals for fields either along the c axis or any direction in the basal plane and give details of the signal as a function of the orthorhombicity parameter. These results correct the theoretical expressions given in some papers along with experiments and provide guidelines for future experiments. We also note that the exact theoretical results obtained disagree with the experimental results reported which give large oscillations in a tetragonal crystal where symmetry dictates that none should be found. With known external fields applied to an orthorhombic crystal, the oscillations expected can also be exactly calculated. The experiments disagree severely with these calculations also. The disagreements of the experimental results with results required by symmetry and those that can be exactly calculated call into question the experimental methods used.

【 授权许可】

Free