Graphene's non-equilibrium fermions reveal Doppler-shifted magnetophonon resonances accompanied by Mach supersonic and Landau velocity effects.
Graphene's non-equilibrium fermions reveal Doppler-shifted magnetophonon resonances accompanied by Mach supersonic and Landau velocity effects.
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DOI：
10.1038/s41467-021-26663-4
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发表时间：
2021-11-04
影响因子：
16.6
通讯作者：
Eaves L
中科院分区：
文献类型：
--
作者：
Greenaway MT;Kumaravadivel P;Wengraf J;Ponomarenko LA;Berdyugin AI;Li J;Edgar JH;Kumar RK;Geim AK;Eaves L
石墨烯的振荡磁阻测量揭示了丰富的新物理。这些现象通常是在小电流下研究的。在大电流下，电子被原子晶格振动驱使远离平衡，因此它们的动能可以超过声子的热能。在这里，我们报道了大电流下单层石墨烯中的三种非平衡现象：(I)当电子经历朗道能级间(LL)跃迁时，横向声学(TA)声子的频率发生“类多普勒”移动和分裂；(Ii)当电子接近超音速时，横向声学声子(TA)声子的内马赫效应；以及(Iii)在临界载流子漂移时，类似于超流体朗道速度的弹性Ll声子跃迁的开始。所有这三种量子现象都可以统一在一个共振方程中。它们为研究其他二维费米子系统中的非平衡现象提供了途径。在石墨烯和量子霍尔系统中，磁振荡揭示了许多有趣的现象，但它们通常是在低电流和平衡状态下测量的。在这里，作者报告了在大电流下石墨烯的磁振荡中观察到的几种非平衡量子效应。
Oscillatory magnetoresistance measurements on graphene have revealed a wealth of novel physics. These phenomena are typically studied at low currents. At high currents, electrons are driven far from equilibrium with the atomic lattice vibrations so that their kinetic energy can exceed the thermal energy of the phonons. Here, we report three non-equilibrium phenomena in monolayer graphene at high currents: (i) a “Doppler-like” shift and splitting of the frequencies of the transverse acoustic (TA) phonons emitted when the electrons undergo inter-Landau level (LL) transitions; (ii) an intra-LL Mach effect with the emission of TA phonons when the electrons approach supersonic speed, and (iii) the onset of elastic inter-LL transitions at a critical carrier drift velocity, analogous to the superfluid Landau velocity. All three quantum phenomena can be unified in a single resonance equation. They offer avenues for research on out-of-equilibrium phenomena in other two-dimensional fermion systems. Magneto-oscillations have revealed many interesting phenomena in graphene and quantum Hall systems, but they are typically measured at low currents and in equilibrium. Here, the authors report several non-equilibrium quantum effects observed in magneto-oscillations in graphene at high currents.
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影响因子：
8.6
作者：
EAVES, L;GUIMARAES, PSS;HILL, G
通讯作者：
HILL, G
影响因子：
8.6
作者：
Martin, AM;Benedict, KA;Eaves, L
通讯作者：
Eaves, L
影响因子：
--
作者：
Landau, L
通讯作者：
Landau, L
影响因子：
3.7
作者：
KALLIN, C;HALPERIN, BI
通讯作者：
HALPERIN, BI
影响因子：
19.6
作者：
Greenaway, M. T.;Vdovin, E. E.;Eaves, L.
通讯作者：
Eaves, L.