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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

(a) χ′ac vs. H plot at temperatures 50–57 K. (b) Selected temperature curves from (a), but offset each other for easy comparison. The notations of HA1 and HA2 indicate skyrmion phase boundaries while HC1 and HC2 indicate conical phase boundaries respectively. The values of HA1 and HA2 are determined by the peaks while HC1 and HC2 are the inflection points in the first derivative of χ′ac vs. H curves. (c) H vs. T phase diagram for Cu2OSeO3, where the skyrmion phase zone is marked in red.
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f4: (a) χ′ac vs. H plot at temperatures 50–57 K. (b) Selected temperature curves from (a), but offset each other for easy comparison. The notations of HA1 and HA2 indicate skyrmion phase boundaries while HC1 and HC2 indicate conical phase boundaries respectively. The values of HA1 and HA2 are determined by the peaks while HC1 and HC2 are the inflection points in the first derivative of χ′ac vs. H curves. (c) H vs. T phase diagram for Cu2OSeO3, where the skyrmion phase zone is marked in red.

Mentions: AC susceptibility is known to be a sensitive technique for revealing coexisting phases in complex magnetic materials, including skyrmion system1525. The H dependent χ′ac curves at 50–58 K are shown in Fig. 4(a) for Cu2OSeO3. Below the vicinity of peak temperature ~56 K as shown Fig. 3b, the evolution of peak anomalies is noticed in the intermediate field region 100 ≤ H ≤ 400 Oe in χ′ac vs. H curves (Fig. 4(a)). It confirms the growth of skyrmion phase1525 as T ≤ 56 K. For low temperatures, the peak anomalies suppress in the χ′ac vs. H curves which indicates the skyrmion phase is almost disappeared for T < 52 K. To demonstrate the typical way of extracting the skyrmion phase boundaries, the χ′ac vs. H curves at selected temperatures T1 = 57 K, T2 = 56 K, T3 = 55 K, T4 = 53 K and T5 = 51 K are shown in Fig. 4(b). The H-T phase diagram with skyrmion zone marked in red for Cu2OSeO3 is successfully constructed and displayed in Fig. 4(c). The evolution of different magnetic phase zones, i.e. helical, conical and skyrmion boundaries are in good agreement with previously published results14.


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)

(a) χ′ac vs. H plot at temperatures 50–57 K. (b) Selected temperature curves from (a), but offset each other for easy comparison. The notations of HA1 and HA2 indicate skyrmion phase boundaries while HC1 and HC2 indicate conical phase boundaries respectively. The values of HA1 and HA2 are determined by the peaks while HC1 and HC2 are the inflection points in the first derivative of χ′ac vs. H curves. (c) H vs. T phase diagram for Cu2OSeO3, where the skyrmion phase zone is marked in red.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: (a) χ′ac vs. H plot at temperatures 50–57 K. (b) Selected temperature curves from (a), but offset each other for easy comparison. The notations of HA1 and HA2 indicate skyrmion phase boundaries while HC1 and HC2 indicate conical phase boundaries respectively. The values of HA1 and HA2 are determined by the peaks while HC1 and HC2 are the inflection points in the first derivative of χ′ac vs. H curves. (c) H vs. T phase diagram for Cu2OSeO3, where the skyrmion phase zone is marked in red.
Mentions: AC susceptibility is known to be a sensitive technique for revealing coexisting phases in complex magnetic materials, including skyrmion system1525. The H dependent χ′ac curves at 50–58 K are shown in Fig. 4(a) for Cu2OSeO3. Below the vicinity of peak temperature ~56 K as shown Fig. 3b, the evolution of peak anomalies is noticed in the intermediate field region 100 ≤ H ≤ 400 Oe in χ′ac vs. H curves (Fig. 4(a)). It confirms the growth of skyrmion phase1525 as T ≤ 56 K. For low temperatures, the peak anomalies suppress in the χ′ac vs. H curves which indicates the skyrmion phase is almost disappeared for T < 52 K. To demonstrate the typical way of extracting the skyrmion phase boundaries, the χ′ac vs. H curves at selected temperatures T1 = 57 K, T2 = 56 K, T3 = 55 K, T4 = 53 K and T5 = 51 K are shown in Fig. 4(b). The H-T phase diagram with skyrmion zone marked in red for Cu2OSeO3 is successfully constructed and displayed in Fig. 4(c). The evolution of different magnetic phase zones, i.e. helical, conical and skyrmion boundaries are in good agreement with previously published results14.

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