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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

Double integrated intensity (DIN) of the original ESR spectra for Cu1-xNMn3+x.(a) for x = 0.1 and (b) for x = 0.3. The inverse DIN is also shown in each panel. The solid line (red) on DIN−1(T) curve indicates a linear fit. The temperatures (T#s) at which DIN−1 departs from the linear dependence on temperature and the Curie temperature TC are indicated by the arrows.
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f4: Double integrated intensity (DIN) of the original ESR spectra for Cu1-xNMn3+x.(a) for x = 0.1 and (b) for x = 0.3. The inverse DIN is also shown in each panel. The solid line (red) on DIN−1(T) curve indicates a linear fit. The temperatures (T#s) at which DIN−1 departs from the linear dependence on temperature and the Curie temperature TC are indicated by the arrows.

Mentions: The transitions in the ESR spectra discussed above can also be found in the double integrated intensity (DIN) of the original dP/dH data plotted in Figure 4(a) and (b) for x = 0.1 and x = 0.3, respectively. For both compounds, the DIN increases remarkably as the temperature approaches TC from above. However, the inverse DIN shows an upturn at T# (~240 K and 355 K for x = 0.1 and 0.3, respectively), which is clearly higher than the Curie temperature, TC. Above T#, the inverse DIN is linearly temperature dependent, suggesting a CW behavior in accordance with that observed for 1/χ(T) (Figure 1).


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)

Double integrated intensity (DIN) of the original ESR spectra for Cu1-xNMn3+x.(a) for x = 0.1 and (b) for x = 0.3. The inverse DIN is also shown in each panel. The solid line (red) on DIN−1(T) curve indicates a linear fit. The temperatures (T#s) at which DIN−1 departs from the linear dependence on temperature and the Curie temperature TC are indicated by the arrows.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Double integrated intensity (DIN) of the original ESR spectra for Cu1-xNMn3+x.(a) for x = 0.1 and (b) for x = 0.3. The inverse DIN is also shown in each panel. The solid line (red) on DIN−1(T) curve indicates a linear fit. The temperatures (T#s) at which DIN−1 departs from the linear dependence on temperature and the Curie temperature TC are indicated by the arrows.
Mentions: The transitions in the ESR spectra discussed above can also be found in the double integrated intensity (DIN) of the original dP/dH data plotted in Figure 4(a) and (b) for x = 0.1 and x = 0.3, respectively. For both compounds, the DIN increases remarkably as the temperature approaches TC from above. However, the inverse DIN shows an upturn at T# (~240 K and 355 K for x = 0.1 and 0.3, respectively), which is clearly higher than the Curie temperature, TC. Above T#, the inverse DIN is linearly temperature dependent, suggesting a CW behavior in accordance with that observed for 1/χ(T) (Figure 1).

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