Guo Xinge, Tong Peng, Lin Jianchao, Yang Cheng, Zhang Kui, Lin Shuai, Song Wenhai, Sun Yuping
School of Science, Hebei University of Science and Technology, Shijiazhuang, China.
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, China.
Front Chem. 2018 Mar 21;6:75. doi: 10.3389/fchem.2018.00075. eCollection 2018.
Negative thermal expansion (NTE) and magnetic properties were investigated for antiperovskite Ga Cr NMn compounds. As increases, the temperature span (Δ) of NTE related with Γ antiferromagnetic (AFM) order is expanded and shifted to lower temperatures. At = 0.1, NTE happens between 256 and 318 K (Δ = 62 K) with an average linear coefficient of thermal expansion, α = -46 ppm/K. The Δ is expanded to 81 K (151-232 K) in = 0.2 with α = -22.6 ppm/K. Finally, NTE is no longer visible for ≥ 0.3. Ferromagnetic order is introduced by Cr doping and continuously strengthened with increasing , which may impede the AFM ordering and thus account for the broadening of NTE temperature window. Moreover, our specific heat measurement suggests the electronic density of states at the Fermi level is enhanced upon Cr doping, which favors the FM order rather than the AFM one.
对反钙钛矿型GaCrNMn化合物的负热膨胀（NTE）和磁性进行了研究。随着[具体参数]增加，与Γ反铁磁（AFM）有序相关的NTE温度跨度（Δ）扩大并向低温方向移动。在[具体参数]=0.1时，NTE发生在256至318K之间（Δ = 62K），平均线性热膨胀系数α = -46 ppm/K。在[具体参数]=0.2时，Δ扩大到81K（151 - 232K），α = -22.6 ppm/K。最后，当[具体参数]≥0.3时，NTE不再可见。Cr掺杂引入了铁磁有序，并且随着[具体参数]增加而持续增强，这可能会阻碍AFM有序，从而解释了NTE温度窗口的拓宽。此外，我们的比热测量表明，Cr掺杂后费米能级处的电子态密度增加，这有利于铁磁有序而非反铁磁有序。
