Coercivity and exchange coupling in PrCo:Co nanocomposite films

Abstract

Magnetic hysteresis and intergrain exchange coupling in nanostructured PrCo:Co composite films have been investigated. The composite thin films were made by multilayer sputtering and subsequent annealing. It is found that the coercivity mechanism is related to film morphology, especially the Co phase fraction. Evidence for the hard-soft-phase exchange coupling has been found and high energy products have been obtained.

Size Dependence of Inter- and Intracluster Interactions in Core–Shell Iron–Iron Oxide Nanoclusters

“…The presence of a relatively steep curve of initial magnetization indicates a nucleation or rotation type of mechanism for H c . 50 Figure 7a compares the field derivatives of the virgin curves for samples S1−S3. The field corresponding to the change in curvature of the virgin curve, the maximum in the field derivative, indicates the amount of applied field required to overcome the anisotropy energy and interaction energy.…”

Remanent enhancement of nanocomposite (Nd, Sm)2Fe14B/α-Fe magnets

“…It has been demonstrated on several occasions [1,2] that the crystallite size of the phases, in particular, that of the soft phase, is important for realizing the remanence enhancement and determining the maximum energy product of the nanocomposite magnets. Much effort has been made to optimize the magnetic properties, by using various preparation methods, such as, mechanical alloying, melt spinning or sputtering [3][4][5][6], or element substitution [7,8]. But the values of the maximum energy product (BH) max achieved experimentally have been much smaller than the ones predicted theoretically.…”

Phase transformation, structure and magnetic properties of (Nd,Pr)–Fe–V–B alloys and their nitrides prepared by mechanical alloying

“…Much effort has been made to optimize the magnetic properties, by using various preparation methods, such as, mechanical alloying [3,4], melt spinning [5], sputtering [6], or element substitution [7,8]. However, the coercivities of these nanocomposite magnets are in many cases small so that their maximum energy products are much lower than the theoretical expectation [1][2][3][4][5][6][7][8].…”

“…Recently, the exchange coupling and remanence enhancements were realized and the maximum energy product of 25. 6 MGOe was achieved in nanocomposite (Nd,Dy)(Fe,Co,Nb,B) 5.5 /a-Fe thin films prepared by sputtering and heat treatments [9], due to a better control of grain sizes and distribution of the magnetic phases in multilayers prepared by sputtering. Although the value of the maximum energy product of the nanocomposite thin films is still lower than one theoretically predicted, our result illustrates that it is necessary to investigate further the structure and magnetic properties of the nanocomposite magnets, in order to have a better understanding of the exchange coupling and the remanence enhancement in the nanocomposite magnets.…”