Proximity-induced hidden order transition in a correlated heterostructure Sr$_2$VO$_3$FeAs
Sunghun Kim, Jong Mok Ok, Hanbit Oh, Chang-il Kwon, Y. Zhang, J. D. Denlinger, S. -K. Mo, F. Wolff-Fabris, E. Kampert, Eun-Gook Moon, C. Kim, Jun Sung Kim, Y. K. Kim
对称性是物理学中最重要的概念之一，它的重要性在相变中通过其自发破缺得到了很大的体现。然而，在强关联系统中，神秘而神秘的相变，对称性描述不适用，已经被发现，并经常被称为隐藏的顺序转变，如发现在，$\it{e.g.}$，高- $T_C$铜酸盐，重费米子超导体，量子自旋液体候选人。在这里，我们报告了一种新的类型的隐藏的顺序过渡的相关异质结构Sr $_2$ VO $_3$ FeAs，其起源是由于异常增强的近藤型邻近耦合之间的本地化自旋的V和巡回电子的FeAs。最值得注意的是，一个完全各向同性的间隙开口，确定角分辨光电子能谱，发生选择性的费米面之一低于$T_{\rm HO}$ $\sim$ 150 K，与一个奇异的行为的比热和各向异性磁电阻的强烈增强。这些意见是不兼容的普遍打破对称驱动的电子间隙开放的情况下，并强调了邻近耦合的关键作用。我们的研究结果表明，相关异质结构提供了一个新的平台，设计和工程异国情调的隐藏顺序相。
英文摘要：
Symmetry is one of the most significant concepts in physics, and its importance has been largely manifested in phase transitions by its spontaneous breaking. In strongly correlated systems, however, mysterious and enigmatic phase transitions, inapplicable of the symmetry description, have been discovered and often dubbed hidden order transitions, as found in, $\it{e.g.}$, high-$T_C$ cuprates, heavy fermion superconductors, and quantum spin liquid candidates. Here, we report a new type of hidden order transition in a correlated heterostructure Sr$_2$VO$_3$FeAs, whose origin is attributed to an unusually enhanced Kondo-type proximity coupling between localized spins of V and itinerant electrons of FeAs. Most notably, a fully isotropic gap opening, identified by angle-resolved photoemission spectroscopy, occurs selectively in one of the Fermi surfaces below $T_{\rm HO}$ $\sim$ 150 K, associated with a singular behavior of the specific heat and a strong enhancement on the anisotropic magnetoresistance. These observations are incompatible with the prevalent broken-symmetry-driven scenarios of electronic gap opening and highlight a critical role of proximity coupling. Our findings demonstrate that correlated heterostructures offer a novel platform for design and engineering of exotic hidden order phases.
Interfacial roughness and proximity effects in superconductor/ferromagnet CuNi/Nb heterostructures
本文报道了用磁控溅射法制备的Nb/Cu $_{60}$ Ni $_{40}$混合超导/铁磁体（S/F）双层膜的结构和电子性质。X射线和中子反射测量表明，沉积在Al $_2$ O $_3$（1 $\bar{1}$ 02）衬底上的异质结构的总界面粗糙度和不同界面粗糙度的垂直相关性都低于沉积在Si（111）衬底上的异质结构。互感实验研究了界面粗糙度对超导转变温度$T_C$的影响。这些测量结果表明，沉积在Al $_2$ O $_3$上的异质结构中的$\sim$比沉积在Si上的异质结构高$T_C$ 4%。我们将这种效应归因于S层中电子的更高平均自由程，这是由界面处的扩散散射的抑制引起的。然而，$T_C$对铁磁层厚度的依赖性在两个系统中没有显著差异，表明库珀对的透明性上的界面粗糙度的微弱影响。
Proximity Magnetism in Mn(Bi,Sb)2Te4-(Bi,Sb)2Te3/MnTe Natural Heterostructures
DEVCOM Army Research Laboratory（DEVCOM陆军研究实验室）；Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology（麻省理工学院等离子体科学与聚变中心弗朗西斯·比特磁实验室）；Department of Electrical Engineering, National Cheng Kung University（国立成功大学电气工程系）；Department of Physics, University of Ottawa（渥太华大学物理系）；Department of Materials Science and Engineering, North Carolina State University（北卡罗来纳州立大学材料科学与工程系）
