Molecular beam epitaxy growth of monolayer hexagonal MnTe₂ on Si(111) substrate*

Abstract

Monolayer MnTe2 stabilized as 1T structure has been theoretically predicted to be a two-dimensional (2D) ferromagnetic metal and can be tuned via strain engineering. There is no naturally van der Waals (vdW) layered MnTe2 bulk, leaving mechanical exfoliation impossible to prepare monolayer MnTe2. Herein, by means of molecular beam epitaxy (MBE), we successfully prepared monolayer hexagonal MnTe2 on Si(111) under Te rich condition. Sharp reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED) patterns suggest the monolayer is atomically flat without surface reconstruction. The valence state of Mn4+ and the atom ratio of ([Te]:[Mn]) further confirm the MnTe2 compound. Scanning tunneling spectroscopy (STS) shows the hexagonal MnTe2 monolayer is a semiconductor with a large bandgap of ∼ 2.78 eV. The valence-band maximum (VBM) locates at the Γ point, as illustrated by angle-resolved photoemission spectroscopy (ARPES), below which three hole-type bands with parabolic dispersion can be identified. The successful synthesis of monolayer MnTe2 film provides a new platform to investigate the 2D magnetism.

Moiré Enhanced Two-Band Superconductivity in a MnTe/NbSe2 Heterojunction

“…Distinct from previously reported Mn chalcogenides of α-MnTe (rock-salt) 38 or MnSe 2 (MnTe 2 ) (pyrite), 39,40 our epitaxial Mn 2 Te 2 phase is stabilized in a DLHC structure with the lowest formation energy when thinned down, 41 similar to CuI or recently discovered Mn 2 Se 2 /NbSe 2 . 42 As shown in Figure 1a, the DLHC phase is in a layered structure with each quadruple layer separated by a vdW gap, within which a pair of buckled honeycomb Mn−Te double-layers are vertically bonded (simply named as MnTe).…”

Manipulate Electronic and Magnetic Properties of Two-Dimensional Manganese Chalcogenides via Hydrogenation

“…Next, we explore the electronic and magnetic properties of the H@MnX monolayers. In pristine MnX monolayers, each Mn 2+ ion possesses a half-occupied d shell (d 5 ) and carries a large formal magnetic moment of 5 μ B . Because of the lack of itinerant carriers, the magnetic couplings in MnX are dominated by the superexchange interaction.…”

“…Nevertheless, J 3 is AFM and is much larger in magnitude than J 1 and J 2 . Such a strong AFM coupling is due to two reasons: (i) One of the two Mn ions connected by J 3 has an occupation state of d 5 , which decides that J 3 must be AFM. (ii) The two Mn−X 4 tetrahedrons connected by J 3 are edgesharing.…”

“…Magnetism in two-dimensional (2D) systems is one of the most fascinating properties because of not only the complex magnetic behavior itself, but also the interplay between magnetism and the other important properties, such as ferroelectricity, valleytronics, and electronic topology . 2D magnetic semiconductors combining magnetism and semiconductivity in one material show great potential on applications for high-performance spintronic devices such as magnetic random access memories. , The recent discoveries of intrinsic ferromagnetism in van der Waals (vdW) monolayers, e.g., CrI 3 , CrGeTe 3 , and CrSBr, have opened a new stage of 2D magnetic semiconductors. − Very recently, the emergence of a new family of 2D magnetic semiconductors, the manganese chalcogenides MnX (X = S, Se, Te), have received much attention . These structures show a layered antiferromagnetic (AFM) order, which is consistent with the Goodenough–Kramer–Anderson rules, − namely, the magnetic coupling between two magnetic ions with half-occupied d orbitals will be strongly AFM.…”

“…3 2D magnetic semiconductors combining magnetism and semiconductivity in one material show great potential on applications for high-performance spintronic devices such as magnetic random access memories. 4,5 The recent discoveries of intrinsic ferromagnetism in van der Waals (vdW) monolayers, e.g., CrI 3 , CrGeTe 3 , and CrSBr, have opened a new stage of 2D magnetic semiconductors. 6−8 Very recently, the emergence of a new family of 2D magnetic semiconductors, the manganese chalcogenides MnX (X = S, Se, Te), have received much attention.…”