High-field ESR spectroscopy of the spin dynamics inLa1−xSrxMnO

Abstract

High-field electron-spin-resonance ͑ESR͒ experiments have been carried out in single crystals of La 1Ϫx Sr x MnO 3 in the concentration range 0рxр0.175. Different quasioptical arrangements have been utilized for frequencies 40рр700 GHz and for magnetic fields Bр12 T. A splitting of the antiferromagnetic resonance ͑AFMR͒ mode is observed in the magnetic field for the parent compound LaMnO 3 , in agreement with the antiferromagnetic structure of this material. Abrupt changes in the AFMR frequencies have been observed around xӍ0.025, and were attributed to a transition between a pure antiferromagnetic and a canted state. For increasing Sr doping the observed AFMR modes are split even in a zero field, which can be naturally explained using a concept of a canted magnetic structure for xϽ0.1. In La 0.825 Sr 0.175 MnO 3 the ESR spectra are consistent with the ferromagnetic and metallic state. The lines of ferromagnetic resonance and ferromagnetic antiresonance can be clearly observed. For intermediate concentrations 0.1рxр0.15 complicated ESR spectra were observed, which can be well explained by a single ferromagnetic resonance mode and taking electrodynamic effects into account.

Anisotropy of magnetic properties in LaMnO3 single crystals

“…The obtained data are in qualitative agreement with the results of previous studies [1][2][3][5][6][7]; some discrepancies may arise because of a small difference in cation and oxygen stoichiometries. The present results confirm existence of canted magnetic structure A a F b type in LaMnO 3 .…”

ESR of the quasi-two-dimensional antiferromagnet CuCrO2with a triangular lattice

“…In the case of magnetic excitations the transmission through the sample can be obtained as a function of either temperature, frequency, or external magnetic field 19 . Due to welldefined polarization of the electromagnetic radiation the orientation of the ac magnetic field is also known in addition to the direction of the static field.…”

Structural and magnetic dimers in the spin-gapped systemCuTe2O5

“…Highfield ESR was performed at a frequency of 185 GHz using a quasi optical technique with backward-wave oscillators as coherent sources for submillimeter wavelength radiation. 9,10 The spectrometer is equipped with a superconducting split-coil magnet with a maximum field of 8T.…”