### Abstract

An analytic solution to the energy barriers of two interacting single domain particles is presented. Identical volumes and uniaxial anisotropies are assumed with easy axes parallel to an external magnetic field. The locations and heights of the system energy barriers are analytically determined when the line joining the two particles is either parallel or perpendicular to the easy axes and the external field. The lowest energy barriers are saddle points of the energy surface and correspond to reversal modes under thermal agitation. When dipole coupling is not strong, the mode of thermal switching is asymmetric fanning or asymmetric coherent rotation, depending upon the bond angle, rather than symmetric fanning or coherent rotation that occurs at the nucleation field. An effective volume that describes the cooperative effect is calculated and good agreement with the numerical results using the Fokker-Planck equation is obtained. The energy barriers can be used to calculate the superparamagnetic relaxation time constants in the high barrier limit.

Original language | English (US) |
---|---|

Pages (from-to) | 5579-5584 |

Number of pages | 6 |

Journal | Journal of Applied Physics |

Volume | 71 |

Issue number | 11 |

DOIs | |

State | Published - 1992 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)

### Cite this

*Journal of Applied Physics*,

*71*(11), 5579-5584. https://doi.org/10.1063/1.351376

**Energy barriers for thermal reversal of interacting single domain particles.** / Chen, Wenjie; Zhang, Shufeng; Bertram, H. Neal.

Research output: Contribution to journal › Article

*Journal of Applied Physics*, vol. 71, no. 11, pp. 5579-5584. https://doi.org/10.1063/1.351376

}

TY - JOUR

T1 - Energy barriers for thermal reversal of interacting single domain particles

AU - Chen, Wenjie

AU - Zhang, Shufeng

AU - Bertram, H. Neal

PY - 1992

Y1 - 1992

N2 - An analytic solution to the energy barriers of two interacting single domain particles is presented. Identical volumes and uniaxial anisotropies are assumed with easy axes parallel to an external magnetic field. The locations and heights of the system energy barriers are analytically determined when the line joining the two particles is either parallel or perpendicular to the easy axes and the external field. The lowest energy barriers are saddle points of the energy surface and correspond to reversal modes under thermal agitation. When dipole coupling is not strong, the mode of thermal switching is asymmetric fanning or asymmetric coherent rotation, depending upon the bond angle, rather than symmetric fanning or coherent rotation that occurs at the nucleation field. An effective volume that describes the cooperative effect is calculated and good agreement with the numerical results using the Fokker-Planck equation is obtained. The energy barriers can be used to calculate the superparamagnetic relaxation time constants in the high barrier limit.

AB - An analytic solution to the energy barriers of two interacting single domain particles is presented. Identical volumes and uniaxial anisotropies are assumed with easy axes parallel to an external magnetic field. The locations and heights of the system energy barriers are analytically determined when the line joining the two particles is either parallel or perpendicular to the easy axes and the external field. The lowest energy barriers are saddle points of the energy surface and correspond to reversal modes under thermal agitation. When dipole coupling is not strong, the mode of thermal switching is asymmetric fanning or asymmetric coherent rotation, depending upon the bond angle, rather than symmetric fanning or coherent rotation that occurs at the nucleation field. An effective volume that describes the cooperative effect is calculated and good agreement with the numerical results using the Fokker-Planck equation is obtained. The energy barriers can be used to calculate the superparamagnetic relaxation time constants in the high barrier limit.

UR - http://www.scopus.com/inward/record.url?scp=36448999455&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=36448999455&partnerID=8YFLogxK

U2 - 10.1063/1.351376

DO - 10.1063/1.351376

M3 - Article

AN - SCOPUS:36448999455

VL - 71

SP - 5579

EP - 5584

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 11

ER -