Gabold, H.MLZ*

2022

Abstract: This work summarises the implementation of MIEZE at the triple axis spectrometer MIRA and the spin wave analysis of BaCdVO(PO_4)_2 and CuMnSb. MIEZE is a variantof the neutron spin echo spectroscopy, which offers high energy resolution on dynamicsof atomic scale. This allows the measurement of quasi-elastic processes, linewidths ofinelastic excitations and fine energy splitting, which is not possible with a standardtriple axis spectrometer. By combining MIEZE with a triple axis spectrometer, oneobtains a energy resolution of MIEZE, while maintaining the flexibility of triple axisspectroscopy in momentum transfer. Compared to other spin echo techniques, MIEZEallows measurements of depolarising samples and in depolarising environments.BaCdVO(PO_4)_2 and CuMnSb are both systems that order antiferromagnetically atlow temperatures. BaCdVO(PO_4)_2 is a quasi two dimensional system and a candidatefor exhibiting a spin nematic phase. BaCdVO(PO_4)_2 was measured in a time-of-flightneutron spectrometer and the resulting spectrum is described by a spin wave model.CuMnSb is a type II antiferromagnet, which shows characteristics of local-moment anditinerant magnetism. CuMnSb was measured with a triple axis spectrometer and the spinwave dispersion at low temperatures has been investigated. It was found that a modelincluding next neighbours up to the fourth order describes the spin wave dispersion best.The obtained exchanged couplings showed that CuMnSb is magnetically frustrated andexhibits, due to the extent range, itinerant interactions.

Keyword(s): Instrument and Method Development (1st) ; Instrument and Method Development (2nd) ; Magnetism (2nd)

1. MIRA (MIRA)
2. E21 (E21)

1. MIRA: Multipurpose instrument (NL6N)