Low-symmetry nonlocal transport in microstructured squares of delafossite metals.
Low-symmetry nonlocal transport in microstructured squares of delafossite metals.
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低对称性非局部输运在微结构方块中的沉积金属。
DOI：
10.1073/pnas.2113185118
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发表时间：
2021-11-23
影响因子：
11.1
通讯作者：
Mackenzie AP
中科院分区：
文献类型：
--
作者：
McGuinness PH;Zhakina E;König M;Bachmann MD;Putzke C;Moll PJW;Khim S;Mackenzie AP
强二维铜铁矿金属是已知纯度最高的化合物之一。其巨大的低温电子平均自由程高达20 µm，允许在弹道范围内制造器件，其中特征器件尺寸小于散射事件之间的平均距离。与以前任何达到这种状态的情况不同，近六边形费米表面的小面化导致了非常强的方向效应。值得注意的是，在弹道制度，这导致从铜铁矿晶体雕刻的正方形的传输响应不显示完整的四重对称性。虽然看起来违反直觉，但我们的观察结果与器件-费米表面组合的整体对称性一致，并且完全遵守非局域输运的Onsager-Büttiker关系。人们一直认为，对基于半导体和石墨烯的二维系统中电子输运的弹道机制的深入研究，已经确立了该领域的大多数关键实验事实。然而，近年来，在准二维的铜铁矿金属中，已经可以获得其他形式的弹道输运，其费米波长比以前研究的典型金属短100倍，其费米表面几乎是六边形，因此具有很强的刻面性。这有一些深刻的后果，从经典的弹道输运实验研究弯曲和霍尔电阻从铜铁矿单晶制成的介观正方形的结果。我们观察到明显的各向异性的弯曲电阻，甚至霍尔电压是强烈不对称的磁场。虽然我们的一些观察是非直观的第一眼看，我们表明，他们可以理解的非本地Landauer-Büttiker分析量身定制的对称性的正方形/六边形的几何形状的组合设备/费米表面系统。非局域输运的特征可以被解析为线性尺寸接近100 μm的正方形，大约是制造器件的晶体的体平均自由程的15倍。
The strongly two-dimensional delafossite metals are among the highest-purity compounds known. Their huge low-temperature electron mean free paths of up to 20 µm allow fabrication of devices in the ballistic regime, in which the characteristic device dimension is shorter than the average distance between scattering events. Unlike any previous case in which this regime has been reached, the faceting of the nearly hexagonal Fermi surfaces leads to extremely strong directional effects. Remarkably, in the ballistic regime, this results in the transport response of squares sculpted from delafossite crystals not showing full fourfold symmetry. Although seemingly counterintuitive, our observations are consistent with the overall symmetry of the device–Fermi surface combination and fully obey the Onsager–Büttiker relations for nonlocal transport. Intense work studying the ballistic regime of electron transport in two-dimensional systems based on semiconductors and graphene had been thought to have established most of the key experimental facts of the field. In recent years, however, additional forms of ballistic transport have become accessible in the quasi–two-dimensional delafossite metals, whose Fermi wavelength is a factor of 100 shorter than those typically studied in the previous work and whose Fermi surfaces are nearly hexagonal in shape and therefore strongly faceted. This has some profound consequences for results obtained from the classic ballistic transport experiment of studying bend and Hall resistances in mesoscopic squares fabricated from delafossite single crystals. We observe pronounced anisotropies in bend resistances and even a Hall voltage that is strongly asymmetric in magnetic field. Although some of our observations are nonintuitive at first sight, we show that they can be understood within a nonlocal Landauer-Büttiker analysis tailored to the symmetries of the square/hexagonal geometries of our combined device/Fermi surface system. Signatures of nonlocal transport can be resolved for squares of linear dimension of nearly 100 µm, approximately a factor of 15 larger than the bulk mean free path of the crystal from which the device was fabricated.
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影响因子：
3.7
作者：
BARANGER, HU;DIVINCENZO, DP;STONE, AD
通讯作者：
STONE, AD
影响因子：
13.6
作者：
Kushwaha P;Sunko V;Moll PJ;Bawden L;Riley JM;Nandi N;Rosner H;Schmidt MP;Arnold F;Hassinger E;Kim TK;Hoesch M;Mackenzie AP;King PD
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3.7
作者：
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通讯作者：
Hassinger, E.
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8.6
作者：
FORD, CJB;WASHBURN, S;HONG, JM
通讯作者：
HONG, JM