Evaluation of Exchange Coupling in α-Fe(100)/Nd2Fe14B(001) Interface

大介, 小川; 邦博, 小池; 幹彦, 大兼; 康夫, 安藤; 孝道, 宮崎; 宏朗, 加藤

doi:10.3379/msjmag.1201r001

Cited by 5 publications

(1 citation statement)

References 13 publications

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“…Exchange spring magnets 1,2 , nanocomposite materials consisting of hard and soft magnetic phases coupled by exchange interaction, have been promising as high-performance magnets 3 , and Nd-Fe-B-based exchange spring magnets are particularly attractive from the viewpoint of low rare-earth metal content. In theoretical studies, (BH) max values of 0.6∼1.0 MJm −3 for Nd-Fe-B-based magnets have been predicted [4][5][6][7] , but such high energy-product values have been difficult to achieve in real materials [8][9][10][11][12][13][14][15][16] . To obtain greater values of (BH) max in real materials, the advanced design of nanostructures is required.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of interface magnetic structure in Nd2Fe14B/(Fe,Co) exchange spring magnets

2016

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The magnetic properties of Nd2Fe14B (NFB)/transition metal (TM = Fe, Co) multilayer systems are studied on the basis of first-principles density functional calculations. Assuming a collinear spin structure, we optimize the model structure under a variety of crystallographic alignments of the NFB layer, and analyze the mechanism of interface magnetic coupling. Improvements in remanent magnetization compared to that of single NFB are observed in NFB(001)/Fe, NFB(110)/Fe, and NFB(100)/Co. On the other hand, in NFB(100)/Fe, remanence degradation due to the anti-parallel magnetization alignment between NFB and Fe layers is observed. In this system, which has the shortest optimized interlayer distance among all considered systems, an itinerant electron magnetism is required around the interface to lower the total energy, and accordingly, anti-ferromagnetic coupling is preferred. The significant difference in property between NFB(100)/Fe and NFB(100)/Co is attributed to the difference between their interface structures, optimized interlayer distances, and magnetic stiffness of TM layers.

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Section: Introductionmentioning

confidence: 99%

First-principles study of interface magnetic structure in Nd2Fe14B/(Fe,Co) exchange spring magnets

2016

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Hard magnetic properties of spacer-layer-tuned NdFeB/Ta/Fe nanocomposite films

et al. 2015

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Anisotropic Ti(20nm)/NdFeB(100nm)Nd(10nm)/Ta(x nm)/Fe(y nm)/Ti(20nm) multilayer films were prepared and the magnetic coupling mechanism between soft/hard-magnetic (SM/HM) layers were systematically studied in order to understand the potential of anisotropic SM/HM nanocomposite magnets. Recoil behaviors were also investigated in films with various thickness of Fe layer. From experimental results, the roles of exchange coupling and magnetostatic coupling in the demagnetization process were clarified, which was further supported by micromagnetic simulations. For different thickness of Ta spacer layer, the demagnetization process was analyzed and the coupling energy was estimated. Our work also indicated that by using proper thickness of Ta spacer layer the (BH)max can be enhanced in the SM/HM nanocomposite magnets by a combination of weakened exchange coupling and magnetostatic coupling.

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Negative exchange coupling in Nd2Fe14B(100)/α-Fe interface

Ogawa

Koike

Mizukami

et al. 2015

Applied Physics Letters

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A model sample with an interface of the Nd2Fe14B(100) plane and the α-Fe phase was fabricated in order to evaluate the exchange-coupling constant Jex between these two ferromagnetic phases. By measuring the ferromagnetic resonance fields and the Kerr loops, the Jex was confirmed to be negative with the value of Jex = −6.5 × 10−4 J/m2, in striking contrast to the positive Jex value for the Nd2Fe14B(001)/α-Fe(100) interface reported previously.

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Evaluation of Exchange Coupling in α-Fe(100)/Nd2Fe14B(001) Interface

Cited by 5 publications

References 13 publications

First-principles study of interface magnetic structure in Nd2Fe14B/(Fe,Co) exchange spring magnets

First-principles study of interface magnetic structure in Nd2Fe14B/(Fe,Co) exchange spring magnets

Hard magnetic properties of spacer-layer-tuned NdFeB/Ta/Fe nanocomposite films

Negative exchange coupling in Nd2Fe14B(100)/α-Fe interface

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