Competing Effect of Biquadratic and Heisenberg Coupling on Magnetic Tunnel Junction Molecular Spintronics Devices

Fuente: arXiv
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Main Authors: Randriambololona, Andoniaina Mariah, Brown, Hayden, Mutunga, Eva, Grizzle, Andrew, DAngelo, Christopher, Tyagi, Pawan
Format: Preprint
Published: 2026
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author Randriambololona, Andoniaina Mariah
Brown, Hayden
Mutunga, Eva
Grizzle, Andrew
DAngelo, Christopher
Tyagi, Pawan
author_facet Randriambololona, Andoniaina Mariah
Brown, Hayden
Mutunga, Eva
Grizzle, Andrew
DAngelo, Christopher
Tyagi, Pawan
contents Heisenberg exchange coupling (HC) and biquadratic exchange coupling (BQC) are known to occur in magnetic tunnel junctions (MTJ) and nanoscale spintronics structures. MTJ-based molecular spintronics devices (MTJMSD) provide a platform to study these interactions and the correlated magnetic behavior they generate. Molecular spin channels formed along the exposed MTJ edge have been shown to produce strong exchange interactions that include HC and BQC, which can drive perpendicular alignment of spin vectors in adjacent ferromagnetic electrodes. Despite their importance, the competing roles of HC and BQC in MTJMSDs remain unclear. Monte Carlo simulations using a three-dimensional Heisenberg model were performed to systematically vary BQC strength under three conditions: no molecular HC, strong parallel HC, and strong antiparallel HC. The resulting magnetic and physical properties of the MTJMSDs were analyzed. Increasing BQC strength produced minimal changes in overall magnetization when strong HC was present, indicating that HC dominates device magnetization. Temporal evolution studies showed that devices with only BQC failed to reach magnetic stability, while devices with both HC and BQC achieved stable magnetic states due to the stabilizing influence of HC. These results show that BQC plays a secondary role in magnetization dynamics and cannot overcome the stronger stabilizing effect of HC. The presence of BQC offers a plausible explanation for experimentally observed magnetic phase orientations beyond simple parallel and antiparallel states in MTJMSDs.
format Preprint
id arxiv_https___arxiv_org_abs_2605_12885
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Competing Effect of Biquadratic and Heisenberg Coupling on Magnetic Tunnel Junction Molecular Spintronics Devices
Randriambololona, Andoniaina Mariah
Brown, Hayden
Mutunga, Eva
Grizzle, Andrew
DAngelo, Christopher
Tyagi, Pawan
Statistical Mechanics
Heisenberg exchange coupling (HC) and biquadratic exchange coupling (BQC) are known to occur in magnetic tunnel junctions (MTJ) and nanoscale spintronics structures. MTJ-based molecular spintronics devices (MTJMSD) provide a platform to study these interactions and the correlated magnetic behavior they generate. Molecular spin channels formed along the exposed MTJ edge have been shown to produce strong exchange interactions that include HC and BQC, which can drive perpendicular alignment of spin vectors in adjacent ferromagnetic electrodes. Despite their importance, the competing roles of HC and BQC in MTJMSDs remain unclear. Monte Carlo simulations using a three-dimensional Heisenberg model were performed to systematically vary BQC strength under three conditions: no molecular HC, strong parallel HC, and strong antiparallel HC. The resulting magnetic and physical properties of the MTJMSDs were analyzed. Increasing BQC strength produced minimal changes in overall magnetization when strong HC was present, indicating that HC dominates device magnetization. Temporal evolution studies showed that devices with only BQC failed to reach magnetic stability, while devices with both HC and BQC achieved stable magnetic states due to the stabilizing influence of HC. These results show that BQC plays a secondary role in magnetization dynamics and cannot overcome the stronger stabilizing effect of HC. The presence of BQC offers a plausible explanation for experimentally observed magnetic phase orientations beyond simple parallel and antiparallel states in MTJMSDs.
title Competing Effect of Biquadratic and Heisenberg Coupling on Magnetic Tunnel Junction Molecular Spintronics Devices
topic Statistical Mechanics
url https://arxiv.org/abs/2605.12885