BaCuO₂₊ₓ中磁性Cu₆和Cu₁₈团簇的反铁磁有序和顺磁行为

Antiferromagnetic Ordering and Paramagnetic Behavior of Ferromagnetic Cu6 and Cu18 Clusters in BaCuO2+x.

作者信息

Wang Z R, Wang X L, Fernandez-Baca J A, Johnston D C, Vaknin D

出版信息

Science. 1994 Apr 15;264(5157):402-4. doi: 10.1126/science.264.5157.402.

DOI:10.1126/science.264.5157.402

Abstract

Magnetization and neutron diffraction measurements on polycrystalline BaCuO2+x revealed a combination of magnetic behaviors. The Cu(6) ring clusters and Cu(18) sphere clusters in this compound had ferromagnetic ground states with large spins 3 and 9, respectively. The Cu(6) rings ordered antiferromagnetically below the Néel temperature T(N) = 15 +/- 0.5 kelvin, whereas the Cu(18) spheres remained paramagnetic down to 2 kelvin. The ordered moment below T(N) was 0.89(5) Bohr magnetons per Cu in the Cu(6) rings, demonstrating that quantum fluctuation effects are small in these atomic clusters. The Cu(18) clusters are predicted to exhibit ferromagnetic intercluster order below about 1 kelvin.

摘要

对多晶BaCuO2+x进行的磁化和中子衍射测量揭示了多种磁行为的组合。该化合物中的Cu(6)环簇和Cu(18)球簇分别具有大自旋3和9的铁磁基态。Cu(6)环在奈尔温度T(N)=15±0.5开尔文以下呈反铁磁有序，而Cu(18)球在降至2开尔文时仍保持顺磁性。在T(N)以下，Cu(6)环中每个铜的有序磁矩为0.89(5)玻尔磁子，这表明量子涨落效应在这些原子簇中很小。预计Cu(18)簇在约1开尔文以下会表现出铁磁簇间有序。