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Cooling field and temperature dependent exchange bias in spin glass/ferromagnet bilayers.

Rui WB, Hu Y, Du A, You B, Xiao MW, Zhang W, Zhou SM, Du J - Sci Rep (2015)

Bottom Line: Significantly, increasing in the magnitude of HFC reduces (increases) the value of HE in the negative (positive) region, resulting in the entire HE∼T curve to move leftwards and upwards.In the meanwhile, HFC variation has weak effects on HC.Thus this work reveals that the SG/FM bilayer system containing intimately coupled interface, instead of a single SG layer, is responsible for the novel EB properties.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.

ABSTRACT
We report on the experimental and theoretical studies of cooling field (HFC) and temperature (T) dependent exchange bias (EB) in FexAu1-x/Fe19Ni81 spin glass (SG)/ferromagnet (FM) bilayers. When x varies from 8% to 14% in the FexAu1-x SG alloys, with increasing T, a sign-changeable exchange bias field (HE) together with a unimodal distribution of coercivity (HC) are observed. Significantly, increasing in the magnitude of HFC reduces (increases) the value of HE in the negative (positive) region, resulting in the entire HE∼T curve to move leftwards and upwards. In the meanwhile, HFC variation has weak effects on HC. By Monte Carlo simulation using a SG/FM vector model, we are able to reproduce such HE dependences on T and HFC for the SG/FM system. Thus this work reveals that the SG/FM bilayer system containing intimately coupled interface, instead of a single SG layer, is responsible for the novel EB properties.

No MeSH data available.


Related in: MedlinePlus

(a) Calculated M-H hysteresis loops at T = 12.52 K after cooling under HFC = 0.2 kOe and 50 kOe, and (b) the corresponding calculated interfacial exchange fields (HJ) as a function of magnetic field, where arrows indicate the magnetizing directions.
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f6: (a) Calculated M-H hysteresis loops at T = 12.52 K after cooling under HFC = 0.2 kOe and 50 kOe, and (b) the corresponding calculated interfacial exchange fields (HJ) as a function of magnetic field, where arrows indicate the magnetizing directions.

Mentions: When the M-H hysteresis loops are measured at the temperatures between T0 and TB (T0 < T < TB), HE may change its sign to become positive and its magnitude is also HFC-dependent. However, in contrast to T < T0, now HE increases with increasing HFC, as the results calculated at T = 12.52 K shown in Fig. 6(a). The M-H hysteresis loop for HFC = 50 kOe has a larger width and shifts more towards right than that for HFC = 0.2 kOe. For the phenomenon of positive HE in this T region, some mechanisms have been proposed. For example, it was attributed to the AFM interfacial coupling141516 or unidirectional coercive field enhancement along the HFC direction in AFM/FM bilayers. It was also argued that the positive HE in SG/FM bilayers is directly due to the RKKY type interaction influenced by T to a different extent2122 or the T-driven SG-to-AFM phase transition23. However, all these interpretations lack microscopic evidence and do not take into account the influence of HFC on positive HE.


Cooling field and temperature dependent exchange bias in spin glass/ferromagnet bilayers.

Rui WB, Hu Y, Du A, You B, Xiao MW, Zhang W, Zhou SM, Du J - Sci Rep (2015)

(a) Calculated M-H hysteresis loops at T = 12.52 K after cooling under HFC = 0.2 kOe and 50 kOe, and (b) the corresponding calculated interfacial exchange fields (HJ) as a function of magnetic field, where arrows indicate the magnetizing directions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562234&req=5

f6: (a) Calculated M-H hysteresis loops at T = 12.52 K after cooling under HFC = 0.2 kOe and 50 kOe, and (b) the corresponding calculated interfacial exchange fields (HJ) as a function of magnetic field, where arrows indicate the magnetizing directions.
Mentions: When the M-H hysteresis loops are measured at the temperatures between T0 and TB (T0 < T < TB), HE may change its sign to become positive and its magnitude is also HFC-dependent. However, in contrast to T < T0, now HE increases with increasing HFC, as the results calculated at T = 12.52 K shown in Fig. 6(a). The M-H hysteresis loop for HFC = 50 kOe has a larger width and shifts more towards right than that for HFC = 0.2 kOe. For the phenomenon of positive HE in this T region, some mechanisms have been proposed. For example, it was attributed to the AFM interfacial coupling141516 or unidirectional coercive field enhancement along the HFC direction in AFM/FM bilayers. It was also argued that the positive HE in SG/FM bilayers is directly due to the RKKY type interaction influenced by T to a different extent2122 or the T-driven SG-to-AFM phase transition23. However, all these interpretations lack microscopic evidence and do not take into account the influence of HFC on positive HE.

Bottom Line: Significantly, increasing in the magnitude of HFC reduces (increases) the value of HE in the negative (positive) region, resulting in the entire HE∼T curve to move leftwards and upwards.In the meanwhile, HFC variation has weak effects on HC.Thus this work reveals that the SG/FM bilayer system containing intimately coupled interface, instead of a single SG layer, is responsible for the novel EB properties.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.

ABSTRACT
We report on the experimental and theoretical studies of cooling field (HFC) and temperature (T) dependent exchange bias (EB) in FexAu1-x/Fe19Ni81 spin glass (SG)/ferromagnet (FM) bilayers. When x varies from 8% to 14% in the FexAu1-x SG alloys, with increasing T, a sign-changeable exchange bias field (HE) together with a unimodal distribution of coercivity (HC) are observed. Significantly, increasing in the magnitude of HFC reduces (increases) the value of HE in the negative (positive) region, resulting in the entire HE∼T curve to move leftwards and upwards. In the meanwhile, HFC variation has weak effects on HC. By Monte Carlo simulation using a SG/FM vector model, we are able to reproduce such HE dependences on T and HFC for the SG/FM system. Thus this work reveals that the SG/FM bilayer system containing intimately coupled interface, instead of a single SG layer, is responsible for the novel EB properties.

No MeSH data available.


Related in: MedlinePlus