Ivek Tomislav, Čulo Matija, Novosel Nikolina, Čebela Maria, Laban Bojana, Čakar Uroš, Rosić Milena
Institut za fiziku, Bijenička cesta 46, HR-10000 Zagreb, Croatia.
"Vinča" Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovića Alasa 12-14, 11351 Belgrade, Serbia.
Nanomaterials (Basel). 2025 May 23;15(11):784. doi: 10.3390/nano15110784.
Manganese oxides (manganites) are among the most studied materials in condensed matter physics due to the famous colossal magnetoresistance and very rich phase diagrams characterized by strong competition between ferromagnetic (FM) metallic and antiferromagnetic (AFM) insulating phases. One of the key questions that remains open even after more than thirty years of intensive research is the exact conductivity mechanism in insulating as well as in metallic phases and its relation to the corresponding magnetic structure. In order to shed more light on this problem, here, we report magnetotransport measurements on sintered nanocrystalline samples of the very poorly explored manganites Ca1-xGdxMnO3 with x=0.05 and x=0.10, in the temperature range 2-300 K, and in magnetic fields up to 16 T. Our results indicate that both compounds at low temperatures exhibit metallic behavior with a peculiar resistivity upturn and a large negative magnetoresistance. We argue that such behavior is consistent with a Kondo-like scattering on Gd impurities coupled with the percolation of FM metallic regions within insulating AFM matrix.
由于著名的巨磁电阻效应以及由铁磁（FM）金属相和反铁磁（AFM）绝缘相之间的强烈竞争所表征的非常丰富的相图，锰氧化物（锰酸盐）是凝聚态物理中研究最多的材料之一。即使经过三十多年的深入研究，仍然悬而未决的关键问题之一是绝缘相和金属相的确切导电机制及其与相应磁结构的关系。为了更清楚地了解这个问题，在此，我们报告了对探索较少的锰酸盐Ca1-xGdxMnO3（x = 0.05和x = 0.10）的烧结纳米晶样品在2 - 300 K温度范围内以及高达16 T磁场下的磁输运测量。我们的结果表明，两种化合物在低温下均表现出金属行为，具有特殊的电阻率上升和大的负磁电阻。我们认为这种行为与Gd杂质上的近藤型散射以及绝缘AFM基质内FM金属区域的渗流相一致。
