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Unexpected observation of splitting of skyrmion phase in Zn doped Cu2OSeO3.

Wu HC, Wei TY, Chandrasekhar KD, Chen TY, Berger H, Yang HD - Sci Rep (2015)

Bottom Line: The effect of Zn doping upon saturation magnetization (MS) indicates that the Zn favors to occupying Cu(II) square pyramidal crystallographic site.The Zn doping concentration is found to affect greatly the M-T and χ'ac-T.H curves.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung, 804 Taiwan.

ABSTRACT
Polycrystalline (Cu1-xZnx)2OSeO3 (0≤x≤0.2) samples were synthesized using solid-state reaction and characterized by X-ray diffraction (XRD). The effect of Zn doping upon saturation magnetization (MS) indicates that the Zn favors to occupying Cu(II) square pyramidal crystallographic site. The AC susceptibility (χ'ac) was measured at various temperatures (χ'ac-T) and magnetic field strengths (χ'ac-H). The Zn doping concentration is found to affect greatly the M-T and χ'ac-T. The skyrmion phase has been inferred from the χ'ac-H data, and then indicated within the H-T phase diagrams for various Zn doping concentrations. The striking and unexpected observation is that the skyrmion phase region becomes split upon Zn doping concentration. Interestingly, second conical boundary accompanied by second skyrmion phase was also observed from dχ'ac/dH vs. H curves. Atomic site disorder created by the chemical doping modulates the delicate magnetic interactions via change in the Dzyaloshinskii-Moriya (DM) vector of distorted Cu(II) square pyramidal, thereby splitting of skyrmion phase might occur. These findings illustrate the potential of using chemical and atomic modification for tuning the temperature and field dependence of skyrmion phase of Cu2OSeO3.

No MeSH data available.


Related in: MedlinePlus

H-T phase diagrams of all (Cu1−xZnx)2OSeO3 (0 ≤ x ≤ 0.2) samples. Skyrmion zone is indicated by two red areas respectively. Solid and dashed green lines denote the two conical phase boundaries respectively.
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f6: H-T phase diagrams of all (Cu1−xZnx)2OSeO3 (0 ≤ x ≤ 0.2) samples. Skyrmion zone is indicated by two red areas respectively. Solid and dashed green lines denote the two conical phase boundaries respectively.

Mentions: Applying the same method as described in Figs 4 and 5, the H-T phase diagrams derived from χ′ac-H data at selected temperatures for each of 8 samples (Cu1−xZnx)2OSeO3 (0 ≤ x ≤ 0.2) are established and shown in Fig. 6, where the boundaries of conical, helical and skyrmion phases are plotted (with various colors) approximately using limited and discrete data points. The surprising finding is that the single skyrmion phase at x = 0 is splitted into two well-defined small branches in two different temperature regions and about the same magnetic field as x ≥ 0.02. Moreover, the second skyrmion phase is hosted by the second conical phase boundary. Both branches of skyrmion phase are systematically shifted towards low temperature side with x. The opening of temperature gap between two branches of skyrmion phase is larger for higher Zn doping concentration. The second skyrmion phase and its associated conical phase boundaries are firmly decoupled with that of the initial skyrmion phase; this can be clearly visible for the doping concentration x ≥ 0.1. Meanwhile, the high-temperature branch becomes harder to extract from the data as x > 0.15. In fact, the trends of splitting, suppression, and decreasing in temperature of skyrmion phases found in Fig. 6 are consistent with those observed in Fig. 3(b).


Unexpected observation of splitting of skyrmion phase in Zn doped Cu2OSeO3.

Wu HC, Wei TY, Chandrasekhar KD, Chen TY, Berger H, Yang HD - Sci Rep (2015)

H-T phase diagrams of all (Cu1−xZnx)2OSeO3 (0 ≤ x ≤ 0.2) samples. Skyrmion zone is indicated by two red areas respectively. Solid and dashed green lines denote the two conical phase boundaries respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4563258&req=5

f6: H-T phase diagrams of all (Cu1−xZnx)2OSeO3 (0 ≤ x ≤ 0.2) samples. Skyrmion zone is indicated by two red areas respectively. Solid and dashed green lines denote the two conical phase boundaries respectively.
Mentions: Applying the same method as described in Figs 4 and 5, the H-T phase diagrams derived from χ′ac-H data at selected temperatures for each of 8 samples (Cu1−xZnx)2OSeO3 (0 ≤ x ≤ 0.2) are established and shown in Fig. 6, where the boundaries of conical, helical and skyrmion phases are plotted (with various colors) approximately using limited and discrete data points. The surprising finding is that the single skyrmion phase at x = 0 is splitted into two well-defined small branches in two different temperature regions and about the same magnetic field as x ≥ 0.02. Moreover, the second skyrmion phase is hosted by the second conical phase boundary. Both branches of skyrmion phase are systematically shifted towards low temperature side with x. The opening of temperature gap between two branches of skyrmion phase is larger for higher Zn doping concentration. The second skyrmion phase and its associated conical phase boundaries are firmly decoupled with that of the initial skyrmion phase; this can be clearly visible for the doping concentration x ≥ 0.1. Meanwhile, the high-temperature branch becomes harder to extract from the data as x > 0.15. In fact, the trends of splitting, suppression, and decreasing in temperature of skyrmion phases found in Fig. 6 are consistent with those observed in Fig. 3(b).

Bottom Line: The effect of Zn doping upon saturation magnetization (MS) indicates that the Zn favors to occupying Cu(II) square pyramidal crystallographic site.The Zn doping concentration is found to affect greatly the M-T and χ'ac-T.H curves.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung, 804 Taiwan.

ABSTRACT
Polycrystalline (Cu1-xZnx)2OSeO3 (0≤x≤0.2) samples were synthesized using solid-state reaction and characterized by X-ray diffraction (XRD). The effect of Zn doping upon saturation magnetization (MS) indicates that the Zn favors to occupying Cu(II) square pyramidal crystallographic site. The AC susceptibility (χ'ac) was measured at various temperatures (χ'ac-T) and magnetic field strengths (χ'ac-H). The Zn doping concentration is found to affect greatly the M-T and χ'ac-T. The skyrmion phase has been inferred from the χ'ac-H data, and then indicated within the H-T phase diagrams for various Zn doping concentrations. The striking and unexpected observation is that the skyrmion phase region becomes split upon Zn doping concentration. Interestingly, second conical boundary accompanied by second skyrmion phase was also observed from dχ'ac/dH vs. H curves. Atomic site disorder created by the chemical doping modulates the delicate magnetic interactions via change in the Dzyaloshinskii-Moriya (DM) vector of distorted Cu(II) square pyramidal, thereby splitting of skyrmion phase might occur. These findings illustrate the potential of using chemical and atomic modification for tuning the temperature and field dependence of skyrmion phase of Cu2OSeO3.

No MeSH data available.


Related in: MedlinePlus