Spatially Modulated Electronic Order in Bulk TMD Superlattices
ORAL · Invited
Abstract
Superimposing large-length-scale electronic, magnetic, or structural modulations over crystalline materials is a powerful method for controlling their electronic behavior; prototypical examples are semiconductor superlattices [1], lithographically patterned two-dimensional electron gases (2DEGs) [2], and now, moiré materials [3].
In parallel with these artificially engineered systems, analogous, spatially periodic modulations can also emerge intrinsically within bulk crystals [4]. In this talk, I will describe an unusual family of bulk van der Waals (vdW) superlattices—hosting alternatingly stacked transition metal dichalcogenide (TMD) and insulating spacer layers—that present a new venue for exploring the interplay between long-wavelength modulations and two-dimensional electronic order [5,6]. I will focus in particular on SrTa₂S₅, where a subtle lattice mismatch between the 2D H-TaS2 TMD layers and spacer layers leads to an emergent long-wavelength stripe modulation of the TMD layer. Through a combination of bulk transport and thermodynamic probes, we find that this structural modulation is mirrored by the electronic and low-temperature superconducting order, giving rise to pronounced transport anisotropy in the normal state and a striking suppression of interlayer coherence within the superconducting state.
I will close by discussing how SrTa₂S₅ and similar systems [7,8] suggest design principles for embedding a wide variety of modulated 2D electronic phases within readily accessible bulk materials, offering a new approach towards engineered quantum phases complementing moiré materials.
References:
[1] L. Esaki and R. Tsu, IBM J. Res. Dev. 14, 61 (1970).
[2] C. Albrecht et al., Phys. Rev. Lett. 83, 2234 (1999).
[3] D. M. Kennes et al., Nat. Phys. 17, 155 (2021).
[4] E. A. Hewat et al., Nature 333, 53 (1988).
[5] A. Devarakonda et al., Science 370, 231 (2020).
[6] A. Devarakonda et al., Nature 631, 526 (2024).
[7] A. V. Kityk et al., Europhys. Lett. 36, 373 (1996).
[8] S. Xie et al., Science 359, 1131 (2018).
In parallel with these artificially engineered systems, analogous, spatially periodic modulations can also emerge intrinsically within bulk crystals [4]. In this talk, I will describe an unusual family of bulk van der Waals (vdW) superlattices—hosting alternatingly stacked transition metal dichalcogenide (TMD) and insulating spacer layers—that present a new venue for exploring the interplay between long-wavelength modulations and two-dimensional electronic order [5,6]. I will focus in particular on SrTa₂S₅, where a subtle lattice mismatch between the 2D H-TaS2 TMD layers and spacer layers leads to an emergent long-wavelength stripe modulation of the TMD layer. Through a combination of bulk transport and thermodynamic probes, we find that this structural modulation is mirrored by the electronic and low-temperature superconducting order, giving rise to pronounced transport anisotropy in the normal state and a striking suppression of interlayer coherence within the superconducting state.
I will close by discussing how SrTa₂S₅ and similar systems [7,8] suggest design principles for embedding a wide variety of modulated 2D electronic phases within readily accessible bulk materials, offering a new approach towards engineered quantum phases complementing moiré materials.
References:
[1] L. Esaki and R. Tsu, IBM J. Res. Dev. 14, 61 (1970).
[2] C. Albrecht et al., Phys. Rev. Lett. 83, 2234 (1999).
[3] D. M. Kennes et al., Nat. Phys. 17, 155 (2021).
[4] E. A. Hewat et al., Nature 333, 53 (1988).
[5] A. Devarakonda et al., Science 370, 231 (2020).
[6] A. Devarakonda et al., Nature 631, 526 (2024).
[7] A. V. Kityk et al., Europhys. Lett. 36, 373 (1996).
[8] S. Xie et al., Science 359, 1131 (2018).
–
Presenters
-
Aravind Devarakonda
- Columbia University