%0 Journal Article
%A Tymoshenko, Y. V.
%A Onykiienko, Y. A.
%A Müller, T.
%A Thomale, R.
%A Rachel, S.
%A Cameron, A. S.
%A Portnichenko, P. Y.
%A Efremov, D. V.
%A Tsurkan, V.
%A Abernathy, D. L.
%A Ollivier, J.
%A Schneidewind, Astrid
%A Piovano, A.
%A Felea, V.
%A Loidl, A.
%A Inosov, D. S.
%T Pseudo-Goldstone Magnons in the Frustrated S=3=2 Heisenberg Helimagnet ZnCr2Se4with a Pyrochlore Magnetic Sublattice
%J Physical review / X
%V 7
%@ 2160-3308
%C College Park, Md.
%I APS
%M FZJ-2017-07932
%P 041049
%D 2017
%X Low-energy spin excitations in any long-range ordered magnetic system in the absence of magnetocrystallineanisotropy are gapless Goldstone modes emanating from the ordering wave vectors. Inhelimagnets, these modes hybridize into the so-called helimagnon excitations. Here we employ neutronspectroscopy supported by theoretical calculations to investigate the magnetic excitation spectrum of theisotropic Heisenberg helimagnet ZnCr2Se4 with a cubic spinel structure, in which spin-3=2 magnetic Cr3þions are arranged in a geometrically frustrated pyrochlore sublattice. Apart from the conventionalGoldstone mode emanating from the ð0 0 qhÞ ordering vector, low-energy magnetic excitations in thesingle-domain proper-screw spiral phase show soft helimagnon modes with a small energy gap of∼0.17 meV, emerging from two orthogonal wave vectors ðqh 00Þ and ð0 qh 0Þ where no magnetic Braggpeaks are present. We term them pseudo-Goldstone magnons, as they appear gapless within linear spinwavetheory and only acquire a finite gap due to higher-order quantum-fluctuation corrections. Our resultsare likely universal for a broad class of symmetric helimagnets, opening up a new way of studying weakmagnon-magnon interactions with accessible spectroscopic methods.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000416432000002
%R 10.1103/PhysRevX.7.041049
%U https://juser.fz-juelich.de/record/840399