Micromagnetism and high temperature coercivity of MnBi/Al multilayers

Rüdiger, Ulrich; Güntherodt, G.; Fumagalli, P.; Thomas, Luc; Parkin, Stuart S. P.; Kent, Andrew D.

doi:10.1063/1.1290466

Cited by 23 publications

(8 citation statements)

References 42 publications

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“…We have used the magnetic exchange energy [4], the uniaxial anisotropy energy [2] and the saturation polarization [8] for this calculation. This suggests that the average grain sizes in all of these MnBi:X ribbons are within the critical single-domain diameter range.…”

Section: Resultsmentioning

confidence: 99%

“…This has made MnBi a material of interest for high-temperature permanent magnet applications. Other interesting properties of MnBi in thin films are the high value of room temperature perpendicular anisotropy [4], the high value of transport spin polarization [5] and an unusual spin correlations leading to a Kondo effect when doped with heavy and noble metals such as Pt and Au [6], [7].…”

Section: Introductionmentioning

confidence: 99%

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Magnetism of MnBi-Based Nanomaterials

et al. 2013

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Nanostructured MnBi ribbons doped with impurity elements including B, C, Fe, Hf, Sm and Tb were prepared using the arc melting and melt-spinning techniques. The melt-spun ribbons were annealed in vacuum furnace at 350 to obtain the intended hexagonal structure. The external impurity doping made a significant change in the magnetic properties of the nanostructured MnBi ribbons including a decrease in saturation magnetization and anisotropy energy (K) and an increase in coercivity . However, Hf and C co-doping showed the opposite effect with a small increase in both and K. Interestingly, the anisotropy energy of the boron doped sample increased by about 15% irrespective of the small decrease in magnetization. A significant increase in of MnBi ribbons was found due to Hf, Tb and Sm doping.as high as 13 kOe was achieved in Hf-doped sample after the sample was aligned in a magnetic field. A thermal hysteresis was observed at the structural phase transition of MnBi, which shifts by about 5 K towards higher temperatures due to impurity doping. The observed magnetic properties of the impurity doped MnBi ribbons are explained as the consequences of the disorder and the competing ferromagnetic and antiferromagnetic interactions.Index Terms-Magnetic anisotropy, melt-spun ribbons, permanent magnet.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetism of MnBi-Based Nanomaterials

et al. 2013

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“…1 MnBi exhibits interesting properties including an extraordinarily large Kerr rotation, 2 a Curie temperature well above room temperature, 3 a high coercivity with a rectangular hysteresis loop, 4 and a large perpendicular anisotropy in thin films at room temperature. 5 Pure MnBi adopts the hexagonal NiAs-type crystal structure at room temperature with lattice constants of a = 4.29 Å and c = 6.12 Å. 6 Around 628 K, it undergoes coupled structural and magnetic phase transitions from a ferromagnetic low-temperature phase ͑LTP͒ to a paramagnetic high-temperature phase ͑HTP͒.…”

Section: Introductionmentioning

confidence: 99%

Structural, magnetic and magneto-transport properties of Pt-alloyed MnBi thin films

Kharel

Skomski

Kirby

et al. 2010

Journal of Applied Physics

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The structural, magnetic and magneto-transport properties of highly c-axis oriented Mn 55−x Pt x Bi 45 ͑x = 0, 1.5, 3, and 4.5͒ thin films have been investigated. The coercivity of the Pt-alloyed thin films increases and the saturation magnetization decreases as the Pt concentration increases. The anisotropy field H o increases as a function of Pt concentration, too but the coercivity increases more rapidly than the anisotropy field. This indicates an enhanced domain-wall pinning, caused by increased interstitial disorder due to the occupancy of regular Mn sites by Pt. The same mechanism explains the reduced magnetization. All samples exhibit a large extraordinary Hall effect with anomalous Hall coefficient about an order of magnitude larger than the ordinary Hall coefficient.

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“…The high-temperature value of K is much higher than that of Nd2Fe14B, the most powerful (highest energy product) permanent magnet developed so far. In thin films, MnBi shows a large room-temperature magnetocrystalline anisotropy perpendicular to the film plane [4]. Other interesting properties of this material in thin film form are the high value of transport spin polarization [5] and an unusual spin correlation leading to a Kondo effect when doped with heavy and noble metals such as Pt and Au [6,7].…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of Pr-alloyed MnBi nanostructures

Kharel¹,

Shah²,

Li³

et al. 2013

J. Phys. D: Appl. Phys.

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The structural and magnetic properties of Pr-alloyed MnBi (short MnBi-Pr) nanostructures with a range of Pr concentrations are investigated. The nanostructures include thin films having Pr concentrations 0, 2, 3, 5, and 9 at.% and melt-spun ribbons having Pr concentrations 0%, 2%, 4%, and 6%, respectively. Addition of Pr into the MnBi lattice has produced a significant change in the magnetic properties of these nanostructures, including an increase in coercivity and structural phase transition temperature, and a decrease in saturation magnetization and anisotropy energy. The highest value of coercivity measured in the films is 23 kOe and in the ribbons is 5.6 kOe. The observed magnetic properties are explained as the consequences of competing ferromagnetic and antiferromagnetic interactions.

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Micromagnetism and high temperature coercivity of MnBi/Al multilayers

Cited by 23 publications

References 42 publications

Magnetism of MnBi-Based Nanomaterials

Magnetism of MnBi-Based Nanomaterials

Structural, magnetic and magneto-transport properties of Pt-alloyed MnBi thin films

Structural and magnetic properties of Pr-alloyed MnBi nanostructures

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