The magnetostriction of cobalt-manganese ferrite

Abstract

Measurements of the magnetostriction constants h1 and h2 are presented for CoxMn1-xFe2O4 in the range 2 K less-than-or-eq, slant T less-than-or-eq, slant 400 K for 0·005 less-than-or-eq, slant x less-than-or-eq, slant 1·12. The contribution of Co2+ ions to the magnetostriction constants Δh1 and Δh2 have been extracted and compared with the theoretical predictions of the single-ion model. It is found that the magnetostriction varies linearly with cobalt concentration only for x<0·20. Close agreement between the theoretical and experimental temperature dependence of Δh1 and Δh2 over the whole temperature range implies a much larger spin-orbit coupling constant (αλ similar 270 cm−1) than has hitherto been thought appropriate to this system, together with a relatively small exchange interaction (βH similar 125 cm−1).

Effect of heat treatment on the magnetic and magnetoelastic properties of cobalt ferrite

“…Previously there has been some disagreement on the degree of inversion in CoFe 2 O 4 [2][3][4] but it is known that the Co 2 + ions in CoFe 2 O 4 have a preference for the B-sites. Also, it is known that the magnetic and magnetostrictive properties of CoFe 2 O 4 depend on the concentration of Co 2 + at the B-sites [5,6]. As a result, changes in the site occupancy of the cations will affect the magnetic and magnetostrictive properties.…”

Atomic-scale mechanisms for magnetostriction in CoFe2O4 and La0.5Subı́as1, Cuartero2, García3 et al. 2019Phys. Rev. B9030View full textAdd to dashboardCite

“…However, these large strains are observed only at very low temperatures and require high magnetic fields, which restrict the use of these materials for practical applications for sensing and actuation. On the other hand, spinel structured ceramic oxides such as cobalt ferrites offer a wide range of interesting properties for application due to its large anisotropic MS of hundreds of ppm in both single-crystal and polycrystalline samples at room temperature and low magnetic fields [6,7].…”

“…At moderate fields of 2 T, the magnetostrictive strain has been reported to be ∼ 450 ppm. On the other hand, CoFe 2 O 4 is a ferrimagnet with a high Curie temperature T C = 793 K and the value of the anisotropic magnetostrictive strain varies from 200 to 400 ppm at room temperature and low magnetic fields (B<1T) for polycrystalline samples [7,21,22]. We expect to extract the magnitude and sign of the changes in individual bond lengths in order to determine which atomic strains are responsible for the macroscopic MS effects in the two samples.…”

Colossal piezomagnetic response in magnetically pressed Zr+4 substituted cobalt ferrites

“…Magnetostrictive Cobalt-ferrite (CFO), an interesting material for magnetoelectric (ME) multiferroic composites because of its high magnetostriction and strain sensitivity, has been identified as a potential material for stress or torque sensor applications 1 – 3 . Since the magnetostrictive property of cobalt ferrite depends on the concentration of cobalt ions (Co +2 ) in the octahedral sites of the spinel lattice, variation in synthesis methods, chemical substitution, processing techniques provide an opportunity to tailor its magnetic and magnetostrictive properties suitable for various applications 4 – 7 . Slonczewski and Tachiki 8 , 9 reported that at lower concentrations Co +2 ions in the octahedral site are surrounded by Fe +3 ions.…”