Spin wave spectrum and exchange interactions in the antiferromagnetic garnet Ca3Cr2Ge3O12 by inelastic neutron scattering

AbstractUnderstanding the spin-wave excitations of chiral magnetic order, such as the skyrmion crystal (SkX), is of fundamental interest to confirm such exotic magnetic order. The SkX is realized by competing Dzyaloshinskii-Moriya and ferromagnetic-exchange interactions with a magnetic field or anisotropy. Here, we compute the dynamical spin structure factor, using Monte Carlo and spin dynamics simulations, extracting the spin-wave spectrum in the SkX, in the vicinity of the paramagnet to SkX transition. Inside the SkX, we find six spin-wave modes, which are supplemented by another mode originating from the ferromagnetic background. Above the critical temperature Ts for the skyrmion crystallization, we find a diffusive regime, reminiscent of the liquid-to-crystal transition, revealing that topological spin texture of skyrmionic character starts to develop above Ts as the precursor of the SkX. We discuss the opportunities for the detection of the spin waves of the SkX using inelastic-neutron-scattering experiments in manganite-iridate heterostructures.

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Inelastic Neutron Scattering Investigations of an Anisotropic Hybridization Gap in the Kondo Insulators: CeT2Al10 (T=Fe, Ru and Os)

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.257.11 ◽

2016 ◽

Vol 257 ◽

pp. 11-25 ◽

Cited By ~ 8

Author(s):

Devashibhai T. Adroja ◽

Y. Muro ◽

Toshiro Takabatake ◽

M.D. Le ◽

H.C. Walker ◽

...

Keyword(s):

Neutron Scattering ◽

Spin Wave ◽

Inelastic Neutron Scattering ◽

Wave Spectrum ◽

Magnetic Ordering ◽

Inelastic Neutron ◽

Spin Gap ◽

Kondo Insulators ◽

Anisotropic Exchange ◽

Magnetic Ordering Temperature

The recent discovery of topological Kondo insulating behaviour in strongly correlated electron systems has generated considerable interest in Kondo insulators both experimentally and theoretically. The Kondo semiconductors CeT2Al10 (T=Fe, Ru and Os) possessing a c-f hybridization gap have received considerable attention recently because of the unexpected high magnetic ordering temperature of CeRu2Al10 (TN=27 K) and CeOs2Al10 (TN=28.5 K) and the Kondo insulating behaviour observed in the valence fluctuating compound CeFe2Al10 with a paramagnetic ground state down to 50 mK. We are investigating this family of compounds, both in polycrystalline and single crystal form, using inelastic neutron scattering to understand the role of anisotropic c-f hybridization on the spin gap formation as well as on their magnetic properties. We have observed a clear sign of a spin gap in all three compounds from our polycrystalline study as well as the existence of a spin gap above the magnetic ordering temperature in T=Ru and Os. Our inelastic neutron scattering studies on single crystals of CeRu2Al10 and CeOs2Al10 revealed dispersive gapped spin wave excitations below TN. Analysis of the spin wave spectrum reveals the presence of strong anisotropic exchange, along the c-axis (or z-axis) stronger than in the ab-plane. These anisotropic exchange interactions force the magnetic moment to align along the c-axis, competing with the single ion crystal field anisotropy, which prefers moments along the a-axis. In the paramagnetic state (below 50 K) of the Kondo insulator CeFe2Al10, we have also observed dispersive gapped magnetic excitations which transform into quasi-elastic scattering on heating to 100 K. We will discuss the origin of the anisotropic hybridization gap in CeFe2Al10 based on theoretical models of heavy-fermion semiconductors.

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Spin-wave dynamics and exchange interactions in multiferroic NdFe3(BO3)4 explored by inelastic neutron scattering

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2017.10.065 ◽

2018 ◽

Vol 451 ◽

pp. 443-449 ◽

Cited By ~ 6

Author(s):

I.V. Golosovsky ◽

A.K. Ovsyanikov ◽

D.N. Aristov ◽

P.G. Matveeva ◽

A.A. Mukhin ◽

...

Keyword(s):

Neutron Scattering ◽

Spin Wave ◽

Inelastic Neutron Scattering ◽

Exchange Interactions ◽

Inelastic Neutron ◽

Wave Dynamics

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The investigation of Neutron Scattering In Spin Waves Theory of Ferromagnetic Crystals

Malaysian Journal of Fundamental and Applied Sciences ◽

10.11113/mjfas.v8n4.151 ◽

2014 ◽

Vol 8 (4) ◽

Author(s):

Azadeh Farzaneh ◽

Mohammad Reza Abdi ◽

Khadije Rezaee Ebrahim Saraee

Keyword(s):

Neutron Scattering ◽

Spin Wave ◽

Cross Section ◽

Inelastic Neutron Scattering ◽

Spin Waves ◽

Wave Theory ◽

Spin Correlation ◽

Inelastic Neutron ◽

Magnetic Behaviour ◽

Spin Interaction

Inelastic neutron scattering, probing the temporal spin-spin correlation at the different microscopic scale, is a powerful technique to study the magnetic behaviour of ferromagnetic crystals. In addition, high penetration power of neutron in samples has made it as a useful way for spin-spin interaction in neutron scattering. Changes in the magnetic cross section in term of different energy transfer and temperatures are calculated for nickel and iron as transition metals in Heisenberg model versus spin wave theory by considering atomic form factor. Finally, the effect of magnetic structure and behaviour of crystal in measuring cross-section shows that increasing temperature results in the Cross-section increase Also, the existence of propagating spin waves below Tc is compared in Ni and Fe in different momentum transfers. The relation of spin wave energy with temperature dependence of nickel has created different behaviour in the changes of cross section rather than iron.

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