Negative magnetoresistance in different nitrogen content EuNbO3-xNx single-crystalline thin films
Negative magnetoresistance in different nitrogen content EuNbO3-xNx single-crystalline thin films
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不同氮含量EuNbO3-xNx单晶薄膜的负磁阻
DOI：
10.1039/d2tc03328c
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发表时间：
2022
影响因子：
6.4
通讯作者：
Chikamatsu Akira
中科院分区：
文献类型：
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作者：
Maruyama Takahiro;Hirose Yasushi;Katayama Tsukasa;Sugisawa Yuki;Sekiba Daiichiro;Hasegawa Tetsuya;Chikamatsu Akira
钙钛矿型氧化氮化铕（EuNbO2N）在低温下表现出巨大的负磁阻（MR > -99%）。为了研究氮在负磁磁共振中的作用，我们制备了不同氮含量（x = 0.6, 0.7和1.0）的EuNbO3 - xNx单晶薄膜，并测量了它们的磁输运特性。所有薄膜的饱和磁化强度为~ 3.0 μB f.u.−1，表明几乎一半的Eu离子存在于三价氧化态，与x无关。随着x的增加，EuNbO3−xNx薄膜的输运性质逐渐由金属性质转变为半导体性质。半导体行为最好用三维变范围跳跃传导来解释，这表明载流子定位是由于氮在阴离子位点的随机分布而发生的。随着x的增加，在2k处的负MR率增加到98%，这与报道的散装EuNbO2N的结果很好地一致。这证明了银硼二氮的巨大磁阻有其内在的起源。我们推测局域化Nb 4d1和Eu2+ 4f电子之间的d-f交换相互作用是导致EuNbO3 - xNx的巨大负MR的关键因素。
Perovskite-type europium niobium oxynitride (EuNbO2N) exhibits colossal negative magnetoresistance (MR > –99%) at low temperatures. To investigate the role of nitrogen in the negative MR, we fabricated EuNbO3−xNx single-crystalline thin films with different nitrogen contents (x = 0.6, 0.7, and 1.0) and measured their magneto-transport properties. All the thin films showed a saturated magnetization of ∼3.0 μB f.u.−1, indicating that almost half of the Eu ions existed in trivalent oxidation states, independent of x. The transport properties of the EuNbO3−xNx thin films gradually changed from metallic to semiconducting as x increased. The semiconducting behaviour was best explained by three-dimensional variable-range hopping conduction, suggesting that carrier localization occurred because of the random distribution of nitrogen at anion sites. As x increased, the negative MR ratio at 2 K increased up to 98%, which was in good agreement with that reported for bulk EuNbO2N. This proved that the colossal MR of EuNbO2N had an intrinsic origin. We speculated that the d–f exchange interaction between the localized Nb 4d1 and Eu2+ 4f electrons was a key factor in the colossal negative MR of EuNbO3−xNx.