Electric field control of exchange-spring behavior

Abstract

We study the electric field control of exchange-spring (ES) behavior in a piezoelectric/ES multi-layer using the micromagnetic simulation method. In the composite, PZT or PZN-PT forms the piezoelectric substrate, while the ES bilayer is composed of hard-magnetic (HM) CoFe2O4 (CFO) and soft-magnetic (SM) Fe3O4 or Co43Fe43B14 materials. The stress as a function of electric-field strength (E) and the external magnetic field was set to align in plane. The results reveal an E-sensitive magnetic property in the PZN-PT/Co43Fe43B14/CFO system. The ES bilayer in this system experienced a transition from rigid magnetism to ES behavior with E changing from 2 MV/m to −2 MV/m. The E-related nucleation field and switching field exhibit strong dependences on the thickness ratio between the HM and SM phases. Additionally, when the magnetic field was applied at an acute angle to the easy axis of the HM or the SM phase, a multi-jump hysteresis loop was observed under a negative E bias. These results may be attributed to a change in the effective magnetic anisotropy constant resulting from the transfer of stress from the piezoelectric substrate to the ES bilayer under an electric field.

Inferface Magnetization Phenomena in Epitaxial Thin Fe3O4/CoxFe3–xO4 Bilayers

“…Exchange-spring behavior has also been reported in CoFe 2 O 4 /CoFe 2 nanoparticles , and ultrathin bilayers . This material system has the substantial advantage to be free from rare earth or noble metals and instead relies on the more widely available transition metals Fe and Co. Also the all-oxide material system Fe 3 O 4 /CoFe 2 O 4 exchange-spring behavior has been investigated in nanocomposites and epitaxial bilayers. , Moreover, the possibility of electric field control of exchange-spring behavior has been reported . Such hard/soft bilayer thin films are of great interest for all-oxide spin tunnel junctions or for spin filtering, for instance. − For this purpose, however, it is of utmost importance to understand the strong exchange coupling and short-range interactions between the charge, spin, and orbital degree of freedom across the Fe 3 O 4 /CoFe 2 O 4 interface.…”

“…14,15 Moreover, the possibility of electric field control of exchange-spring behavior has been reported. 16 Such hard/soft bilayer thin films are of great interest for all-oxide spin tunnel junctions or for spin filtering, for instance. 17−19 For this purpose, however, it is of utmost importance to understand the strong exchange coupling and short-range interactions between the charge, spin, and orbital degree of freedom across the with respect to the underlying mechanisms of the exchangespring process.…”

Micromagnetic study of magnetization reversal in exchange spring systems with mutually orthogonal anisotropies

“…Understanding the surface and interface magnetism of exchange spring systems is crucial in finetuning their properties. Researchers have adopted several methods, such as spin wave excitations [11e13], heat assistance [6,7,14], electric field control [15], and insertion of non-magnetic spacers [16], to explore exchange spring systems. In addition, many theoretical studies have explored magnetization reversal in soft/hard multilayered structures [17,18].…”