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Unusual ferromagnetic critical behavior owing to short-range antiferromagnetic correlations in antiperovskite Cu(1-x)NMn(3+x) (0.1 ≤ x ≤ 0.4).

Lin J, Tong P, Cui D, Yang C, Yang J, Lin S, Wang B, Tong W, Zhang L, Zou Y, Sun Y - Sci Rep (2015)

Bottom Line: In addition, the paramagnetic susceptibility of all the samples deviates from the Curie-Weiss (CW) law just above T(C).This deviation is gradually smeared as x increases.The short-range antiferromagnetic ordering above T(C) revealed by our electron spin resonance measurement explains both the unusual critical behavior and the breakdown of the CW law.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China.

ABSTRACT
For ferromagnets, varying from simple metals to strongly correlated oxides,the critical behaviors near the Curie temperature (T(C)) can be grouped into several universal classes. In this paper, we report an unusual critical behavior in manganese nitrides Cu(1-x)NMn(3+x) (0.1 ≤ x ≤ 0.4). Although the critical behavior below T(C) can be well described by mean field (MF) theory, robust critical fluctuations beyond the expectations of any universal classes are observed above T(C) in x = 0.1. The critical fluctuations become weaker when x increases, and the MF-like critical behavior is finally restored at x = 0.4. In addition, the paramagnetic susceptibility of all the samples deviates from the Curie-Weiss (CW) law just above T(C). This deviation is gradually smeared as x increases. The short-range antiferromagnetic ordering above T(C) revealed by our electron spin resonance measurement explains both the unusual critical behavior and the breakdown of the CW law.

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Related in: MedlinePlus

Phase diagram for Cu1-xNMn3+x with 0 ≤ x ≤ 0.5.TC represents the ferromagnetic (FM) Curie temperature, and TS represents the tetragonal-cubic structural transition temperature. T* denotes the temperature below which 1/χ(T) deviates from the Curie-Weiss law, and T# is the onset temperature below which short-range antiferromagnetic ordering (SR AFM) occurs and coexists with the paramagnetic (PM) matrix.
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f6: Phase diagram for Cu1-xNMn3+x with 0 ≤ x ≤ 0.5.TC represents the ferromagnetic (FM) Curie temperature, and TS represents the tetragonal-cubic structural transition temperature. T* denotes the temperature below which 1/χ(T) deviates from the Curie-Weiss law, and T# is the onset temperature below which short-range antiferromagnetic ordering (SR AFM) occurs and coexists with the paramagnetic (PM) matrix.

Mentions: Figure 6 is a phase diagram for Cu1-xNMn3+x with x up to 0.5 based on our previous measurements of the bulk magnetic susceptibility and temperature-dependent X-ray diffraction35. When x increases, the structural transition temperature TS decreases and finally disappears above x = 0.4; however, TC shifts toward higher temperatures. Similar trends were reported by Takenaka et al in nitrogen-deficient CuN1-δMn334, where the nitrogen deficiency causes a reduction of TS and an increase of TC. Based on the results discussed above, a temperature zone of SR AFM ordering against the PM background can be added to the phase diagram, which isolates the low-temperature FM ordered state from the high-temperature PM state.


Unusual ferromagnetic critical behavior owing to short-range antiferromagnetic correlations in antiperovskite Cu(1-x)NMn(3+x) (0.1 ≤ x ≤ 0.4).

Lin J, Tong P, Cui D, Yang C, Yang J, Lin S, Wang B, Tong W, Zhang L, Zou Y, Sun Y - Sci Rep (2015)

Phase diagram for Cu1-xNMn3+x with 0 ≤ x ≤ 0.5.TC represents the ferromagnetic (FM) Curie temperature, and TS represents the tetragonal-cubic structural transition temperature. T* denotes the temperature below which 1/χ(T) deviates from the Curie-Weiss law, and T# is the onset temperature below which short-range antiferromagnetic ordering (SR AFM) occurs and coexists with the paramagnetic (PM) matrix.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300457&req=5

f6: Phase diagram for Cu1-xNMn3+x with 0 ≤ x ≤ 0.5.TC represents the ferromagnetic (FM) Curie temperature, and TS represents the tetragonal-cubic structural transition temperature. T* denotes the temperature below which 1/χ(T) deviates from the Curie-Weiss law, and T# is the onset temperature below which short-range antiferromagnetic ordering (SR AFM) occurs and coexists with the paramagnetic (PM) matrix.
Mentions: Figure 6 is a phase diagram for Cu1-xNMn3+x with x up to 0.5 based on our previous measurements of the bulk magnetic susceptibility and temperature-dependent X-ray diffraction35. When x increases, the structural transition temperature TS decreases and finally disappears above x = 0.4; however, TC shifts toward higher temperatures. Similar trends were reported by Takenaka et al in nitrogen-deficient CuN1-δMn334, where the nitrogen deficiency causes a reduction of TS and an increase of TC. Based on the results discussed above, a temperature zone of SR AFM ordering against the PM background can be added to the phase diagram, which isolates the low-temperature FM ordered state from the high-temperature PM state.

Bottom Line: In addition, the paramagnetic susceptibility of all the samples deviates from the Curie-Weiss (CW) law just above T(C).This deviation is gradually smeared as x increases.The short-range antiferromagnetic ordering above T(C) revealed by our electron spin resonance measurement explains both the unusual critical behavior and the breakdown of the CW law.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China.

ABSTRACT
For ferromagnets, varying from simple metals to strongly correlated oxides,the critical behaviors near the Curie temperature (T(C)) can be grouped into several universal classes. In this paper, we report an unusual critical behavior in manganese nitrides Cu(1-x)NMn(3+x) (0.1 ≤ x ≤ 0.4). Although the critical behavior below T(C) can be well described by mean field (MF) theory, robust critical fluctuations beyond the expectations of any universal classes are observed above T(C) in x = 0.1. The critical fluctuations become weaker when x increases, and the MF-like critical behavior is finally restored at x = 0.4. In addition, the paramagnetic susceptibility of all the samples deviates from the Curie-Weiss (CW) law just above T(C). This deviation is gradually smeared as x increases. The short-range antiferromagnetic ordering above T(C) revealed by our electron spin resonance measurement explains both the unusual critical behavior and the breakdown of the CW law.

No MeSH data available.


Related in: MedlinePlus