| Autor: |
Roy, Nirmal, Sen, Arpita, Sen, Prasenjit, Banerjee, S. S. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 3/31/2020, Vol. 127 Issue 12, p1-6, 6p, 1 Black and White Photograph, 1 Chart, 4 Graphs |
| Abstrakt: |
We study magnetic, transport, and thermal properties of Co2C and Co3C nanocomposites mixed in a 1:1 ratio. The nanocomposite has clusters with an average diameter of 40 ± 15 nm. We show that the behavior of the nanocomposite is completely different from that of only Co3C or Co2C. We observed that with decreasing temperature, the saturation magnetization MS(T) increases, with a steep rise seen below 100 K. A detailed analysis shows that the increase in MS(T) down to 100 K is explained via a surface spin freezing model. However, below 100 K, the steep increase in MS(T) is explained by a finite size effect related to the confinement of spin waves within nanoparticles. Heat capacity measurements show a broad peak at 100 K along with a low temperature anomaly at 43 K (=Tex). Resistance measurements of the nanocomposite show metallic behavior at high T with an anomalous feature appearing at Tex, which is near the T regime, where MS(T) begins to increase steeply. A measurement of the temperature gradients across the sample thickness indicates an abrupt change in thermal conductivity at Tex. Our results suggest a transformation from a magnetically coupled state with a continuous spectrum of spin waves into a magnetically decoupled state below 100 K with confined spin waves. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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