Nontrivial Response of Nanoscale Uniaxial Magnets to an Alternating Field

Miyashita, Seiji; Saito, Keiji; Raedt, de Hans

doi:10.1103/physrevlett.80.1525

Cited by 36 publications

(28 citation statements)

References 32 publications

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“…As a consequence of this, the final state of the system consists of ordered domains whose finite size depend upon the velocity of the parameter variation [29]. A nontrivial oscillation of the magnetization [30] and the connection between symmetry and CDT [31] has been investigated * Electronic address: victor@physik.tu-berlin.de in a finite size periodically-driven Ising model. Furthermore, under the effect of a nonadiabatic external control of the transverse field, the Ising chain exhibits dynamical freezing of the response [32,33], and synchronization with the external driving in the asymptotic dynamics as a consequence of destructive interference in time [34].…”

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confidence: 99%

Nonequilibrium quantum phase transitions in the Ising model

et al. 2012

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We establish a set of nonequilibrium quantum phase transitions in the Ising model driven under monochromatic nonadiabatic modulation of the transverse field. We show that besides the Isinglike critical behavior, the system exhibits an anisotropic transition which is absent in equilibrium. The nonequilibrium quantum phases correspond to states which are synchronized with the external control in the long-time dynamics.PACS numbers: 32.80. Qk, 05.30.Rt, 37.30.+i, 03.75.Kk One of the more intriguing hallmarks of many-body systems is that at zero temperature quantum fluctuations can drive the system to a drastic change of state, commonly known as a quantum phase transition (QPT). A paradigmatic model for QPTs is the one-dimensional Ising model [1]. Recently, experimental realizations of one-dimensional spin chains have been suggested, where a quantum simulation of the system close to the phase transition is possible, and a wide freedom on the control of the parameters is achieved [2][3][4][5][6][7]. The quantum control of many-body systems by a driving field has attracted considerable interest, both theoretical and experimental, with workers from very different communities beginning to look at driven models [8][9][10][11][12][13][14][15][16][17]. The possibility of manipulating the quantum state of a system by means of a classical external control allows one to explore novel states of matter and effective interactions which are absent in equilibrium [16][17][18][19]. In the presence of an external control, quantum resonances and symmetries play an important role [20][21][22][23]. In particular, as a consequence of a generalized parity in the extended Hilbert space [20], under the effect of periodic driving the tunneling can be slowed down or totally suppressed in a perfect coherent way, a phenomenon commonly referred to as coherent destruction of tunneling (CDT) [24,25]. Rather recently, the extension of this concept to manybody systems has been addressed in the context of the Mott-insulator-superfluid transition in ultracold systems both theoretically [13] as well as experimentally [15], and in a two-mode Bose-Hubbard model with time-dependent self-interaction strength [11].The dynamics of one-dimensional spin chains has been addressed extensively when the system is driven slowly through the critical point [26][27][28], where there is a diverging relaxation time and correlation length, and the dynamics cannot be adiabatic in the thermodynamic limit. As a consequence of this, the final state of the system consists of ordered domains whose finite size depend upon the velocity of the parameter variation [29]. A nontrivial oscillation of the magnetization [30] and the connection between symmetry and CDT [31] has been investigated * Electronic address: victor@physik.tu-berlin.de in a finite size periodically-driven Ising model. Furthermore, under the effect of a nonadiabatic external control of the transverse field, the Ising chain exhibits dynamical freezing of the response [32,33], and synchronization with the exter...

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Nonequilibrium quantum phase transitions in the Ising model

et al. 2012

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“…This quantum-mechanical transition has been studied from the point of view of the nonadiabatic transition. [7][8][9][10] There are two characteristic features of each nonadiabatic transition. 9 One is the localization of the transition because it occurs only around avoided level crossing points.…”

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Effects of the environment on nonadiabatic magnetization process in uniaxial molecular magnets at very low temperatures

1999

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“…It would also be worthwhile to extend this approach to finite temperatures to investigate the thermodynamic properties of the molecule and to study the phenomenon of thermally assisted tunneling [10]. For models of the Ising kind, a nontrivial response of the magnetization is known for an alternating field [11]. A study of the same in our model is currently in progress.…”

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Magnetization ofMn12acetate in a slowly varying magnetic field: A quantum mechanical study

2001

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Beginning with a Heisenberg spin Hamiltonian for the manganese ions in the M n 12 Ac molecule, we find a number of low-energy states of the system. We use these states to solve the time-dependent Schrödinger equation and find the magnetization of the molecule in the presence of a slowly varying magnetic field. We study the effects of the field sweep rate, fourth order anisotropic spin interactions and a transverse field on the weights of the different states as well as the magnetization steps which are known to occur in the hysteresis plots in this system. We find that the fourth order term and a slow field sweep rate are crucial for obtaining prominent steps in magnetization in the hysteresis plots.

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Nontrivial Response of Nanoscale Uniaxial Magnets to an Alternating Field

Cited by 36 publications

References 32 publications

Nonequilibrium quantum phase transitions in the Ising model

Nonequilibrium quantum phase transitions in the Ising model

Effects of the environment on nonadiabatic magnetization process in uniaxial molecular magnets at very low temperatures

Magnetization ofMn12acetate in a slowly varying magnetic field: A quantum mechanical study

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