Depth-dependent Spin Dynamics in TbMnO3 Thin Films Measured by Low Energy Muon Spin Relaxation

We report on low energy muon measurements performed on 100 nm and 28 nm thin epitaxial, highly strained and twin free TbMnO3 films grown on (110) YAlO3 substrates by pulsed laser deposition (λ = 248 nm, ν = 2 Hz, TS = 760°C). These investigations were done at the LEM beamline at the PSI, Switzerland which allowed for depthdependent analysis of the muon spin relaxation rate as a function of temperature. A clear decrease of the relaxation rates could be observed in regions near the substrate/thin film interface compared to measurements at the surface or in the middle of the films. This behavior could be attributed to a straininduced change of the Tb spin dynamics. Furthermore, it could be shown that the films are fully magnetic below a temperature of 40 – 50 K, which agrees well with susceptibility measurements performed on these films as well as with the bulk literature value of TN,Mn = 41 K.