Interaction-Induced Transition at Low Densities in Silicon Inversion Layer

Bloss, Walter L.; Sham, L. J.; Винтер, В. Г.

doi:10.1103/physrevlett.43.1529

Cited by 64 publications

(15 citation statements)

References 23 publications

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“…Given the large quasiparticle band gap, 3.7 eV (36), it would be challenging to realize this high level of hole doping by conventional electrostatic schemes. Similar spontaneous valley polarization was observed in 2D electronic systems, such as the inversion layer in silicon in the 1970s (38). More recently, giant paramagnetism in monolayer MoS 2 was reported (39), with an unconfirmed yet possible spontaneous ferromagnetism proposed.…”

Section: Induced Magnetic Response In Nonmagnetic 2d Materialssupporting

confidence: 67%

Two-dimensional magnetic crystals and emergent heterostructure devices

Gong

Zhang

2019

Science

1,263

931

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Magnetism, originating from the moving charges and spin of elementary particles, has revolutionized important technologies such as data storage and biomedical imaging, and continues to bring forth new phenomena in emergent materials and reduced dimensions. The recently discovered two-dimensional (2D) magnetic van der Waals crystals provide ideal platforms for understanding 2D magnetism, the control of which has been fueling opportunities for atomically thin, flexible magneto-optic and magnetoelectric devices (such as magnetoresistive memories and spin field-effect transistors). The seamless integration of 2D magnets with dissimilar electronic and photonic materials opens up exciting possibilities for unprecedented properties and functionalities. We review the progress in this area and identify the possible directions for device applications, which may lead to advances in spintronics, sensors, and computing.

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Section: Induced Magnetic Response In Nonmagnetic 2d Materialssupporting

confidence: 67%

Two-dimensional magnetic crystals and emergent heterostructure devices

Gong

Zhang

2019

Science

1,263

931

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“…This remarkable observation points to a giant magnetic susceptibility, presumably stemming from exchange interactions, enabling new possibilities for the control and manipulation of the valley degree of freedom. Interesting open questions include the temperature dependence of the magnetic response and its possible relation to the theoretical prediction of spontaneous valley polarization in silicon inversion layers [25]. In parallel, our measurements unequivocally demonstrate the validity of the polaron picture for describing resonant absorption/reflection experiments.…”

supporting

confidence: 62%

“…We also note that the B z -dependence of valley polarized n e shows saturation for |B z | ≥ 5 T, indicating a deviation from a purely paramagnetic response that is consistent with super-paramagnetism [24]. We speculate that reduced screening and relatively heavy electron mass may ensure that exchange and correlation energies in monolayer MoSe 2 exceed kinetic energy even for densities of order 1.6 × 10 12 cm −2 , resulting in the observed giant paramagnetic response at T = 4 K. Investigation of higher quality samples at lower temperatures could be used to investigate if an interaction induced phase transition to a ferromagnetic state is possible [25].…”

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confidence: 55%

Giant Paramagnetism-Induced Valley Polarization of Electrons in Charge-Tunable Monolayer MoSe2

et al. 2017

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For applications exploiting the valley pseudospin degree of freedom in transition metal dichalcogenide monolayers, efficient preparation of electrons or holes in a single valley is essential. Here, we show that a magnetic field of 7 Tesla leads to a nearcomplete valley polarization of electrons in MoSe 2 monolayer with a density 1.6 × 10 12 cm −2 ; in the absence of exchange interactions favoring single-valley occupancy, a similar degree of valley polarization would have required a pseudospin g-factor exceeding 40. To investigate the magnetic response, we use polarization resolved photoluminescence as well as resonant reflection measurements. In the latter, we observe gate voltage dependent transfer of oscillator strength from the exciton to the attractiveFermi-polaron: stark differences in the spectrum of the two light helicities provide a confirmation of valley polarization. Our findings suggest an interaction induced giant paramagnetic response of MoSe 2 , which paves the way for valleytronics applications. Hall effect [10,11] as well as a modification of the exciton spectrum [12,13]. Investigation of one of the most interesting features of this material system, namely the valley pseudospin degree of freedom [14,15], has been hampered by the difficulty in obtaining a high-degree of valley polarization of free electrons or holes [16]. While circularly polarized excitation ensures that the excitons are generated in a single valley [17][18][19], significant transfer of valley polarization from excitons to itinerant electrons or holes has not been observed.Here, we report a strong paramagnetic response of a two dimensional electron system (2DES) in a charge-tunable monolayer MoSe 2 sandwiched between two hexagonal boron-nitride (hBN) layers (Fig. 1A). Figure 1B shows the corresponding single-particle energy-band diagram when an external arXiv:1701.01964v1 [cond-mat.mes-hall]

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“…This behavior is consistent with a transition from two-valley to one-valley occupation in (100) Si inversion layers as predicted by Bloss, Sham, and Vinter. 3 The density at which it occurs and the magnitude of the shift in transition energy are both in good agreement with theoretical predictions; however, other possible models 10 cannot be ruled out at this time.…”

supporting

confidence: 75%