arXiv subjects

Igor Píš

Publications and source records attributed to Igor Píš.

4 recordsLinked to original sources

arXiv2026

Graphene-Confined Growth of Few-Layer PtSe2 via One-Step Selenization

Platinum diselenide (PtSe$_2$), a member of the transition metal dichalcogenide (TMD) family, is a promising material for next-generation electronic and optoelectronic applications due to its thickness-dependent properties, transitioning from semimetallic in bulk to semiconducting behavior at the few-layer limit. However, the scalable fabrication of large-area ultrathin PtSe$_2$ films remains challenging, as conventional selenization of pre-deposited Pt layers often leads to undesired three-dimensional clustered growth. This work explores a novel strategy for promoting two-dimensional growth of PtSe$_2$ by employing a graphene-mediated confinement approach. The method involves coating a Pt layer with graphene oxide (GO), followed by annealing in a selenium atmosphere, which results in the simultaneous formation of PtSe$_2$ and the reduction of GO to graphene. The graphene overlayer acts as a physical confinement layer, suppressing vertical growth and enabling the synthesis of graphene-confined PtSe$_2$ heterostructures on centimetre-scale substrates and promoting lateral connectivity of PtSe$_2$ regions observed by STEM. Scanning transmission electron microscopy (STEM), including temperature-resolved in situ atomic-resolution measurements, was used to investigate the influence of selenization temperature on the growth mechanism and structural evolution of PtSe$_2$ films. The results show that graphene confinement stabilizes lateral growth and promotes the formation of few-layer films with improved structural ordering. Beyond PtSe$_2$, this graphene-assisted approach provides a general strategy for fabricating and stabilizing ultrathin TMD layers, including those prone to environmental degradation, providing a new outlook for enabling detailed studies of their intrinsic properties.

cond-mat.mtrl-sci↗

arXiv2023

A ferromagnetic Eu-Pt surface compound grown below hexagonal boron nitride

One of the fundamental applications for monolayer-thick 2D materials is their use as protective layers of metal surfaces and in-situ intercalated reactive materials in ambient conditions. Here we investigate the structural, electronic, and magnetic properties, as well as the chemical stability in air of a very reactive metal, Europium, after intercalation between a hexagonal boron nitride (hBN) layer and a Pt substrate. We demonstrate that Eu intercalation leads to a hBN-covered ferromagnetic EuPt$_2$ surface alloy with divalent Eu$^{2+}$ atoms at the interface. We expose the system to ambient conditions and find a partial conservation of the di-valent signal and hence the Eu-Pt interface. The use of a curved Pt substrate allows us to explore the changes in the Eu valence state and the ambient pressure protection at different substrate planes. The interfacial EuPt$_2$ surface alloy formation remains the same, but the resistance of the protecting hBN layer to ambient conditions is reduced, likely due to a rougher surface and a more discontinuous hBN coating.

cond-mat.mtrl-sci↗

arXiv2019

Growth, Morphology and Stability of Au in Contact with the Bi2Se3(0001) Surface

We report a combined microscopy and spectroscopy study of Au deposited on the Bi2Se3(0001) single crystal surface. At room temperature Au forms islands, according to the Volmer-Weber growth mode. Upon annealing to 100° C the Au deposits are not stable and assemble into larger and thicker islands. The topological surface state of Bi2Se3 is weakly affected by the presence of Au. Contrary to other metals, such as Ag or Cr, a strong chemical instability at the Au/Bi2Se3 interface is ruled out. Core level analysis highlights Bi diffusion toward the surface of Au islands, in agreement with previous findings, while chemical interaction between Au and atomic Se is limited at the interfacial region. For the investigated range of Au coverages, the Au/Bi2Se3 heterostructure is inert towards CO and CO2 exposure at low pressure (10-8 mbar) regime.

cond-mat.mtrl-sci↗

arXiv2018

Fe intercalation under graphene and hexagonal boron nitride in-plane heterostructure on Pt(111)

Metal nanostructures confined between sp2 hybridized 2D materials and solid supports are attracting attention for their potential application in new nanotechnologies. Model studies under well-defined conditions are valuable for understanding the fundamental aspects of the phenomena under 2D covers. In this work we investigate the intercalation of iron atoms through a single layer of mixed graphene and hexagonal boron nitride on Pt(111) using a combination of spectroscopic and microscopic techniques. Thermally activated diffusion of iron proceeds preferentially under graphene and only partially under hexagonal boron nitride areas. When oxygen is coadsorbed with iron, the intercalation rate is higher, and formation of B2O3 and oxygenated B-C species is observed. Our results suggest the possibility of confining ferromagnetic layers under heterostructures of graphene and hexagonal boron nitride with potential technological implications in the fields of spintronics, magnetic data storage or chemistry under 2D covers.

physics.chem-ph↗