Magnetic Phase Transitions in Ferromagnetic Alloys

Magnetic phase transitions refer to transformations between distinct magnetic orders in solid alloys under variations of temperature, magnetic or electric field, strain and optical excitation. In ferromagnetic alloys this spans classical second-order Curie transitions in nickel- and cobalt-based systems to first-order metamagnetic switches exemplified by equiatomic iron-rhodium. The cooperative interplay of spin, electronic and lattice degrees of freedom gives rise to rich phenomena such as phase coexistence, thermal hysteresis, supercooling and abrupt domain avalanches. Advances in time-resolved spectroscopy, mesoscale patterning and strain engineering have revealed microscopic pathways for angular-momentum transfer, the influence of confinement on transition temperatures and the role of lattice entropy. Insights into these mechanisms underpin emerging applications in ultralow-energy memory, spintronic logic, heat-assisted recording and magnetic refrigeration.

Research from Nature Portfolio

Recent studies have shown that femtosecond laser pulses can induce ultrafast magnetization in iron-rhodium heterostructures, generating spin currents that directly probe angular-momentum flow between electron and magnon reservoirs. Investigations of lateral spin pumping during the antiferromagnetic–ferromagnetic transition in ultrathin films have quantified sharply enhanced damping associated with mixed-phase domains, offering new routes to optimise spin-current generation and sink efficiencies. Foundational work on patterned mesoscale FeRh stripes has demonstrated dramatic asymmetry between cooling-driven avalanche transitions and gradual heating-driven reordering, emphasising the importance of long-range ferromagnetic correlations and large activation volumes well beyond those observed in continuous films.

Magnetic Phase Transitions in Ferromagnetic Alloys publication trend

The graph below shows the total number of articles in magnetic phase transitions in ferromagnetic alloys across all publications each year (not limited to Nature Index journals).

Technical terms

Metamagnetic transition: A first-order switch between antiferromagnetic and ferromagnetic states under external stimuli such as temperature or field.

Spin current: A flow of spin angular momentum, carried by electrons or magnons, capable of transferring torque without net charge transport.

Spin pumping: Dynamic transfer of angular momentum from a precessing magnetic layer into an adjacent medium, manifesting as enhanced damping.

Phase coexistence: The simultaneous presence of two magnetic phases (for example AFM and FM) within a single material near a first-order transition.

Magnetoresistance: Change in electrical resistance arising from variations in magnetic order or applied magnetic fields.

Hysteresis: Dependence of a system’s state on its prior history, characteristic of first-order transitions exhibiting supercooling or superheating.

References

1. Spin current driven by ultrafast magnetization of FeRh. Nature Communications (2023).
2. Spin pumping during the antiferromagnetic–ferromagnetic phase transition of iron–rhodium. Nature Communications (2020).
3. Colossal magnetic phase transition asymmetry in mesoscale FeRh stripes. Nature Communications (2016).
4. Preserving Metamagnetism in Self-Assembled FeRh Nanomagnets. ACS Applied Materials & Interfaces (2023).
5. Electric‐Field Control of Magnetic Order: From FeRh to Topological Antiferromagnetic Spintronics. Advanced Electronic Materials (2018).
6. Impact of lattice dynamics on the phase stability of metamagnetic FeRh: Bulk and thin films. Physical Review B (2016).