Journal of Research on Many-body Systems

Journal of Research on Many-body Systems

Analytical study of the spin tunneling effect by considering dipole excitations in single-molecular magnet Mn12

Document Type : Full length research Paper

Authors
Yousef Yousefi
Fathemah Ramezanpoor
Mohammad Reza Benam
Department of Physics, Faculty of Science, Payame Noor University, Tehran, Iran
10.22055/jrmbs.2020.15327
Abstract
Spin tunneling effect in Single Molecule Magnet Mn12 is studied by instanton calculation technique using SU(2) spin coherent state in real parameter as a trial function. For this SMM, tunnel splitting ( steps in hysteresis loop) arises due to the presence of a Berry phase in action, which causes interference between tunneling trajectories (instantons). In the analytical calculation, the assumption of the linearity of the instanton solution in term of applied magnetic field is used. It is observed that the number of quenching points of magnetic tunneling, the number of steps in hysteresis loop, are equal to the number of points obtained from numerical calculation. Of course, the position of the points (the magnitude of the field in which the tunneling amplitude is zero) is different.
Keywords
Coherent State
Spin Tunneling
Instanton
dipole Excitation
[1] R. Sessoli, H.L.Tsai, A.R. Schake, S. Wang, J.B. Vincent, K. Folting, D. Gatteschi, G. Christou, D.N. Hendrickson High-spin molecules [Mn12O12(O2CR)16(H2O)4], Journal of the American Chemical Society 115 5(1993) 1804-1816.
https://doi.org/10.1021/ja00058a027
[2] R. Sessoli, D. Gatteschi, A. Caneschi, M.A. Novak, Magnetic bistability in a metal-ion cluster, Nature 365 (1993) 141.  https://doi.org/10.1038/365141a0
[3] M.A. Novak, R. Sessoli, A. Caneschi, D. Gatteschi, Magnetic properties of a Mn cluster organic compound, Journal of Magnetism and Magnetic Materials 146 (1995) 211.  https://doi.org/10.1016/0304-8853(94)00860-4
[4] J.R. Friedman, M.P. Sarachik, J. Tejada, J. Maciejewski, R. Ziolo, Steps in the hysteresis loops of a high‐spin molecule, Journal of Applied Physics 79 (1996) 6031. https://doi.org/10.1063/1.361837
[5] J.R. Friedman, M.P. Sarachik, J. Tejada, R. Ziolo, Macroscopic Measurement of Resonant Magnetization Tunneling in High-Spin Molecules, Physical Review Letters 76 (1996) 3830. https://doi.org/10.1103/PhysRevLett.76.3830
[6] J.M. Hernandez, X.X. Zhang, F. Luis, J. Tejada, J.R. Friedman, M.P. Sarachik, R. Ziolo, Evidence for resonant tunneling of magnetization in Mn12 sacetate complex, Physical Review B 55 (1997) 5858. https://doi.org/10.1103/PhysRevB.55.5858
[7] D. Loss, D.P. DiVincenzo, G. Grinstein, Quantum tunneling and dissipation in nanometer-scale magnets, Physica B 189 (1993) 189-203. https://doi.org/10.1016/0921-4526(93)90160-8
[8] L. Thomas, F. Lionti, R. Ballou, D. Gatteschi, R. Sessoli, B. Barbara, Macroscopic quantum tunnelling of magnetization in a single crystal of nanomagnets, Nature 383 (1996) 145. DOI:10.1038/383145a0
[9] J. Tejada, R. Ziolo, X.X. Zhang, Quantum Tunneling of Magnetization in Nanostructured Materials, Chemistry of Materials, 8 (1996) 1784. https://doi.org/10.1021/cm9602003
[10] J.R. Friedman, M.P. Sarachik, Single-Molecule Nanomagnets, Annual Review of Condensed Matter Physics, 1 (2010) 109–128. https://doi.org/10.1146/annurev-conmatphys-070909-104053
[11] M.S. Foss-Feig, J.R. Friedman, Geometric-phase-effect tunnel-splitting oscillations in single-molecule magnets with fourth-order anisotropy induced by orthorhombic distortion, EuroPhysics Letters, 86 2 (2009). Doi:10.1209/0295-5075/86/27002
 [12] Y. Yousefi, Kh. Kh. Muminov, Semi classical description of isotropic Non-Heisenberg magnets for spin S=3/2 and linear quadrupole excitation dynamics, Iranian Journal of Physics Research, 12 2(2012) 179-183. http://ijpr.iut.ac.ir/article-1-1071-en.html
[13] B. Felsager, Geometry Particls and Fields, Springer, New York, (1998)
[14] E.M. Chudnovsky, L. Gunther, Quantum tunneling of magnetization in small ferromagnetic particles, Physical Review Letters, 60 8 (1988) 661–664. https://doi.org/10.1103/PhysRevLett.60.661
[15] E.M. Chudovsky, X. Martinez, Non-Kramers freezing and unfreezing of tunneling in the biaxial spin model, Europhysics Letters, 50 3 (2000) 395–401. 10.1209/epl/i2000-00282-0
[16] A. Garg, Topologically Quenched Tunnel Splitting in Spin Systems without Kramers Degeneracy, Europhysics Letters 22 (1993) 205. https://doi.org/10.1209/0295-5075/22/3/008

  • Receive Date 18 January 2018
  • Revise Date 14 August 2019
  • Accept Date 28 December 2019