Emergence of a hidden magnetic phase in LaFe11.8Si1.2 investigated by inelastic neutron scattering as a function of field and temperature

Fuente: arXiv
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Auteurs principaux: Morrison, K., Betouras, J. J., Venkat, G., Ewings, R. A., Caruana, A., Skokov, K., Gutfleisch, O., Cohen, L. F.
Format: Preprint
Publié: 2022
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author Morrison, K.
Betouras, J. J.
Venkat, G.
Ewings, R. A.
Caruana, A.
Skokov, K.
Gutfleisch, O.
Cohen, L. F.
author_facet Morrison, K.
Betouras, J. J.
Venkat, G.
Ewings, R. A.
Caruana, A.
Skokov, K.
Gutfleisch, O.
Cohen, L. F.
contents The NaZn13 type itinerant magnet LaFe13-xSix has seen considerable interest due to its unique combination of large magnetocaloric effect and low hysteresis. Here we demonstrate, with a combination of magnetometry, bespoke microcalorimetry and inelastic neutron scattering that this is due to the presence of paramagnetic spin fluctuations, which build up as the critical point is approached. While thermal measurements show significant latent heat independent changes in the heat capacity, inelastic neutron scattering reveals the presence of broad quasielastic scattering that persists above Tc, in addition to a finite Q quasielastic peak at Q=0.52 A$^{-1}$ (close to a 100 Bragg reflection in this system at Q = 0.54 A$^{-1}$). This finite Q quasielastic peak appears only in the paramagnetic state and when in proximity to the itinerant metamagnetic transition. We associate these observations with a hidden competing phase and spin fluctuations close to the transition temperature and magnetic field, that persist across the magnetic transition.
format Preprint
id arxiv_https___arxiv_org_abs_2203_06010
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Emergence of a hidden magnetic phase in LaFe11.8Si1.2 investigated by inelastic neutron scattering as a function of field and temperature
Morrison, K.
Betouras, J. J.
Venkat, G.
Ewings, R. A.
Caruana, A.
Skokov, K.
Gutfleisch, O.
Cohen, L. F.
Strongly Correlated Electrons
Materials Science
Other Condensed Matter
The NaZn13 type itinerant magnet LaFe13-xSix has seen considerable interest due to its unique combination of large magnetocaloric effect and low hysteresis. Here we demonstrate, with a combination of magnetometry, bespoke microcalorimetry and inelastic neutron scattering that this is due to the presence of paramagnetic spin fluctuations, which build up as the critical point is approached. While thermal measurements show significant latent heat independent changes in the heat capacity, inelastic neutron scattering reveals the presence of broad quasielastic scattering that persists above Tc, in addition to a finite Q quasielastic peak at Q=0.52 A$^{-1}$ (close to a 100 Bragg reflection in this system at Q = 0.54 A$^{-1}$). This finite Q quasielastic peak appears only in the paramagnetic state and when in proximity to the itinerant metamagnetic transition. We associate these observations with a hidden competing phase and spin fluctuations close to the transition temperature and magnetic field, that persist across the magnetic transition.
title Emergence of a hidden magnetic phase in LaFe11.8Si1.2 investigated by inelastic neutron scattering as a function of field and temperature
topic Strongly Correlated Electrons
Materials Science
Other Condensed Matter
url https://arxiv.org/abs/2203.06010