Spin-phonon dispersion in magnetic materials

Gu, Mingqiang1; Bai, Y. H.2; Zhang, G. P.3; George, Thomas F.4,5

2022-09-14

10.1088/1361-648X/ac7f17

JOURNAL OF PHYSICS-CONDENSED MATTER   Impact Factor & Quartile

0953-8984

1361-648X

Microscopic coupling between the electron spin and the lattice vibration is responsible for an array of exotic properties from morphic effects in simple non magnets to magnetodielectric coupling in multiferroic spinels and hematites. Traditionally, a single spin-phonon coupling constant is used to characterize how effectively the lattice can affect the spin, but it is hardly enough to capture novel electromagnetic behaviors to the full extent. Here, we introduce a concept of spin-phonon dispersion to project the spin moment change along the phonon crystal momentum direction, so the entire spin change can be mapped out. Different from the phonon dispersion, the spin-phonon dispersion has both positive and negative frequency branches even in the equilibrium ground state, which correspond to the spin enhancement and spin reduction, respectively. Our study of bcc Fe and hcp Co reveals that the spin force matrix, that is, the second-order spatial derivative of spin moment, is similar to the vibrational force matrix, but its diagonal elements are smaller than the off-diagonal ones. This leads to the distinctive spin-phonon dispersion. The concept of spin-phonon dispersion expands the traditional Elliott-Yafet theory in nonmagnetic materials to the entire Brillouin zone in magnetic materials, thus opening the door to excited states in systems such as CoF2 and NiO, where a strong spin-lattice coupling is detected in the THz regime.

spin phonon dispersion magnetism force matrix Elliot-Yafet

SCI ; EI

English

First

Foundation for Distinguished Young Talents in Higher Education of Guangdong[2020KQNCX064] ; Shenzhen Science and Technology Innovation Council[JCYJ20210324104812034] ; Natural Science Foundation of Guangdong Province[2021A1515110389] ; U.S. Department of Energy[DE-FG02-06ER46304] ; Office of Science of the U.S. Department of Energy[DE-AC02-05CH11231]

Physics

Physics, Condensed Matter

WOS:000825105700001

IOP Publishing Ltd

20223012422210

Cobalt compounds ; Electrospinning ; Ground state ; Hematite ; Lattice theory ; Lattice vibrations ; Magnetic materials ; Magnetic moments ; Nanofibers ; Nickel oxide ; Spin dynamics

Minerals:482.2 ; Magnetism: Basic Concepts and Phenomena:701.2 ; Magnetic Materials:708.4 ; Nanotechnology:761 ; Inorganic Compounds:804.2 ; Fiber Chemistry and Processing:819.3 ; Mathematical Statistics:922.2 ; Atomic and Molecular Physics:931.3 ; Solid State Physics:933 ; Crystal Lattice:933.1.1

PHYSICS

Web of Science

1.Southern Univ Sci & Technol, Dept Phys, Shenzhen 518055, Peoples R China
2.Indiana State Univ, Off Informat Technol, Terre Haute, IN 47809 USA
3.Indiana State Univ, Dept Phys, Terre Haute, IN 47809 USA
4.Univ Missouri, Dept Chem & Biochem, St Louis, MO 63121 USA
5.Univ Missouri, Dept Phys & Astron, St Louis, MO 63121 USA

Gu, Mingqiang,Bai, Y. H.,Zhang, G. P.,et al. Spin-phonon dispersion in magnetic materials[J]. JOURNAL OF PHYSICS-CONDENSED MATTER,2022,34(37).

Gu, Mingqiang,Bai, Y. H.,Zhang, G. P.,&George, Thomas F..(2022).Spin-phonon dispersion in magnetic materials.JOURNAL OF PHYSICS-CONDENSED MATTER,34(37).

Gu, Mingqiang,et al."Spin-phonon dispersion in magnetic materials".JOURNAL OF PHYSICS-CONDENSED MATTER 34.37(2022).