Abstract-Terahertz optomagnetism: Nonlinear THz excitation of GHz spin waves in antiferromagnetic FeBO 3

E. A. Mashkovich, K. A. Grishunin, R. V. Mikhaylovskiy, A. K. Zvezdin, R. V. Pisarev, M. B. Strugatsky, P. C. M. Christianen, Th. Rasing, and A. V. Kimel

https://journals.aps.org/prl/accepted/f0076Yf6Q491f36a663a7df0eb0a420e30dde4d37

A nearly single cycle intense terahertz (THz) pulse with peak electric and magnetic fields of 0.5 MV/cm and 0.16 T, respectively, excites both modes of spin resonances in the weak antiferromagnet FeBO3. The high frequency quasi-antiferromagnetic mode is excited resonantly and its amplitude scales linearly with the strength of the THz magnetic field, whereas the low frequency quasiferromagnetic mode is excited via a nonlinear mechanism that scales quadratically with the strength of the THz electric field and can be regarded as a THz inverse Cotton-Mouton effect. THz opto-magnetism is shown to be more energy efficient than similar effects reported previously for the near-infrared spectral range

Abstract-Terahertz-driven magnetism dynamics in the orthoferrite DyFeO3

A. H. M. Reid, Th. Rasing, R. V. Pisarev, H. A. Dürr, M. C. Hoffmann

(Submitted on 5 Jun 2017)

      https://arxiv.org/abs/1706.01545

Terahertz driven magnetization dynamics are explored in the orthoferrite DyFeO3. A high-field, single cycle THz pulse is used to excite magnon modes in the crystal together with other resonances. Both quasi-ferromagnetic and quasi-antiferromagnetic magnon modes are excited and appear in time-resolved measurements of the Faraday rotation. Other modes are also observed in the measurements of the time-resolved linear birefringence. Analysis of the excitation process reveals that despite larger than expected electro-optical susceptibility it is mainly the THz magnetic field that couples to the quasi-ferromagnetic and quasi-antiferromagnetic magnon branches.

Abstract-Selective Excitation of Terahertz Magnetic and Electric Dipoles in Er3+ Ions by Femtosecond Laser Pulses in ErFeO3

R. V. Mikhaylovskiy, T. J. Huisman, R. V. Pisarev, Th. Rasing, and A. V. Kimel

Phys. Rev. Lett. 118, 017205 – Published 6 January 2017

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.017205

We show that femtosecond laser pulse excitation of the orthoferrite ErFeO3 triggers pico- and subpicosecond dynamics of magnetic and electric dipoles associated with the low energy electronic states of the Er3+ ions. These dynamics are readily revealed by using polarization sensitive terahertz emission spectroscopy. It is shown that by changing the polarization of the femtosecond laser pulse one can excite either electric dipole-active or magnetic dipole-active transitions between the Kramers doublets of the I415/2 ground state of the Er3+ (4f11) ions. These observations serve as a proof of principle of polarization-selective control of both electric and magnetic degrees of freedom at terahertz frequencies, opening up new vistas for optical manipulation of magnetoelectric materials.

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Abstract-Selective excitation of terahertz magnetic and electric dipoles in Er3+ ions by femtosecond laser pulses in ErFeO3

R. V. Mikhaylovskiy, T. J. Huisman, R. V. Pisarev, Th. Rasing, and A. V. Kimel

https://journals.aps.org/prl/accepted/b3076Ya2D7914e5035ed35a67890ca74eb7f0f2a6

We show that femtosecond laser pulse excitation of the orthoferrite 1 ErFeO3 triggers pico- and subpicosecond dynamics of magnetic and electric dipoles associated with the low energy electronic states of the Er3+ ions. These dynamics are readily revealed by using polarization sensitive terahertz emission spectroscopy. It is shown that by changing the polarization of the femtosecond laser pulse one can excite either electric dipole-active or magnetic dipole-active transitions between the Kramers doublets of the 4I15/2 ground state of the Er3+ (4f11) ions. These observations serve as a proof-of7 principle of polarization-selective control of both electric and magnetic degrees of freedom at terahertz frequencies, opening new doors for optical manipulation of magneto-electric materials

Abstract-Inverse magneto-refraction as a mechanism for laser modification of spin-spin exchange parameters and subsequent terahertz emission from iron oxides

R. V. Mikhaylovskiy, E. Hendry, A. Secchi, J. H. Mentink, M. Eckstein, A. Wu, R. V. Pisarev, V. V. Kruglyak, M. I. Katsnelson, Th. Rasing, A. V. Kimel

(Submitted on 22 Dec 2014)

Inverse magneto-refraction as a mechanism for laser modification of spin-spin exchange parameters and subsequent terahertz emission from iron oxides

Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins. Here we propose a novel scenario for coupling between the electric field of light and spins via optical modification of the exchange interaction, one of the strongest quantum effects, the strength of which can reach 1000 Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be called the inverse magneto-refraction, is allowed in a material of any symmetry. Its existence is corroborated by the experimental observation of THz emission by magnetic-dipole active spin resonances optically excited in a broad class of iron oxides with a canted spin configuration. From its strength we estimate that a sub-picosecond laser pulse with a moderate fluence of ~ 1 mJ/cm^2 acts as a pulsed effective magnetic field of 0.01 Tesla, arising from the optically perturbed balance between the exchange parameters. Our findings are supported by a low-energy theory for the microscopic magnetic interactions between non-equilibrium electrons subjected to an optical field which suggests a possibility to modify the exchange interactions by light over 1 %.

Subjects:	Strongly Correlated Electrons (cond-mat.str-el); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Cite as:	arXiv:1412.7094 [cond-mat.str-el]
	(or arXiv:1412.7094v1 [cond-mat.str-el] for this version)

Submission history

From: Rostislav Mikhaylovskiy [view email]
[v1] Mon, 22 Dec 2014 18:55:13 GMT (2198kb)

Abstract-Terahertz emission spectroscopy of laser-induced spin dynamics in TmFeO3 and ErFeO3 orthoferrites

R. V. Mikhaylovskiy, E. Hendry, V. V. Kruglyak, R. V. Pisarev, Th. Rasing, and A. V. Kimel
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.184405

Using the examples of laser-induced spin-reorientation phase transitions in TmFeO3 and ErFeO3 orthoferrites, we demonstrate that terahertz emission spectroscopy can obtain novel information about ultrafast laser-induced spin dynamics, which is not accessible by more common all-optical methods. The power of the method is evidenced by the fact that, in addition to the expected quasi-ferromagnetic and quasi-antiferromagnetic modes of the iron sublattices, terahertz emission spectroscopy enables detection of a resonance optically excited at an unexpected frequency of ∼0.3–0.35 THz. By recording how the amplitude and phase of the excited oscillations depend on temperature and applied magnetic field, we show that the unexpected mode has all the features of a spin resonance of the Fe3+ ions. We suggest that it can be assigned to transitions between the multiplet sublevels of the 6A1 ground state of the Fe+3ions occupying rare-earth positions.

DOI: http://dx.doi.org/10.1103/PhysRevB.90.184405

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• Published 5 November 2014
• Received 22 July 2014
• Revised 23 September 2014

©2014 American Physical Society