Correlation between Spin and Orbital Dynamics during Laser-Induced Femtosecond Demagnetization

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

2021-07-08

10.1021/acs.jpcc.1c03409

Journal of Physical Chemistry C   影响因子和分区

1932-7447

1932-7455

Spin and orbital angular momenta are two intrinsic properties of an electron and are responsible for the physics of a solid. How the spin and orbital evolve with respect to each other on several hundred femtoseconds is largely unknown, but it is at the center of laser-induced ultrafast demagnetization. In this paper, we introduce a concept of the spin-orbital correlation diagram, where spin angular momentum is plotted against orbital angular momentum, much like the position-velocity phase diagram in classical mechanics. We use four sets of highly accurate time-resolved X-ray magnetic circular dichroism data to construct four correlation diagrams for iron and cobalt. To our surprise, a pattern emerges. The trace on the correlation diagram for iron is an arc, and at the end of demagnetization, it has a pronounced cusp. The correlation diagram for cobalt is different and appears more linear but with kinks. We carry out first-principles calculations with two different methods: time-dependent density functional theory (TDDFT) and time-dependent Liouville density functional theory. These two methods agree that the experimental findings for both Fe and Co are not due to experimental errors. It is the spin-orbit coupling that correlates the spin dynamics to the orbital dynamics. Microscopically, Fe and Co have different orbital occupations, which leads to distinctive correlation diagrams. We believe that this correlation diagram presents a useful tool to better understand spin and orbital dynamics on an ultrafast time scale. A brief discussion on the magnetic anisotropy energy is also provided.

SCI ; EI

英语

其他

U.S. Department of Energy[DE-FG02-06ER46304] ; Office of Science of the U.S. Department of Energy[DE-AC02-05CH11231]

Chemistry ; Science & Technology - Other Topics ; Materials Science

Chemistry, Physical ; Nanoscience & Nanotechnology ; Materials Science, Multidisciplinary

WOS:000672734100033

AMER CHEMICAL SOC

20212910658027

Angular momentum ; Calculations ; Cobalt ; Cobalt metallography ; Demagnetization ; Density functional theory ; Dichroism ; Femtosecond lasers ; Iron ; Iron metallography ; Magnetic anisotropy ; Spin orbit coupling

Iron:545.1 ; Nonferrous Metals and Alloys excluding Alkali and Alkaline Earth Metals:549.3 ; Magnetism: Basic Concepts and Phenomena:701.2 ; Light/Optics:741.1 ; Mathematics:921 ; Atomic and Molecular Physics:931.3

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

Zhang, G. P.,Gu, Mingqiang,Bai, Y. H.,et al. Correlation between Spin and Orbital Dynamics during Laser-Induced Femtosecond Demagnetization[J]. Journal of Physical Chemistry C,2021,125(26):14461-14467.

Zhang, G. P.,Gu, Mingqiang,Bai, Y. H.,Jenkins, T. L.,&George, Thomas F..(2021).Correlation between Spin and Orbital Dynamics during Laser-Induced Femtosecond Demagnetization.Journal of Physical Chemistry C,125(26),14461-14467.

Zhang, G. P.,et al."Correlation between Spin and Orbital Dynamics during Laser-Induced Femtosecond Demagnetization".Journal of Physical Chemistry C 125.26(2021):14461-14467.