arXiv subjects

Ayanesh Maiti

Publications and source records attributed to Ayanesh Maiti.

6 recordsLinked to original sources

arXiv2026

Thermodynamics of $T_{\rm c}$ suppression in far-overdoped Tl$_2$Ba$_2$CuO$_6$

The physical origin of the suppression of superconductivity with hole doping in overdoped cuprates remains unclear. We measure the electronic specific heat of microgram-scale Tl$_2$Ba$_2$CuO$_6$ crystals and find sharp superconducting anomalies persisting far into the overdoped regime. A weak-coupling BCS-like framework incorporating the known Fermi surface and cation disorder quantitatively reproduces the observed anomalies for $T_{\rm c}=14$-$25$ K and their weak doping dependence. The results show $T_{\rm c}(p)$ to be driven predominantly by a smoothly decreasing pairing strength.

cond-mat.supr-con↗

arXiv2026

Cryogenic focused-ion-beam microstructuring enabling quantitative $c$-axis transport measurements in Tl$_2$Ba$_2$CuO$_{6+\delta}$

Absolute transport measurements in correlated quantum materials are often limited by disorder, inhomogeneity, geometric uncertainty, and small crystal size. Focused ion beam (FIB) technology offers a route to overcome many of these limitations by enabling transport devices with precisely defined geometry to be fabricated from lamellae extracted from carefully selected regions of a crystal, but its application to cuprate superconductors has been hindered by ion-beam-induced damage. Here we study the clean overdoped cuprate Tl2201 and show that conventional FIB processing causes thermally driven oxygen loss, while cryogenic FIB microstructuring largely suppresses this degradation and preserves the crystal structure from the bulk to the atomic scale. Microstructured devices quantitatively reproduce established in-plane resistivity and Hall carrier density measurements without rescaling. Applying this approach to $c$-axis transport, we obtain absolute $\rho_c(T)$ values approximately three times larger than previously reported, bringing the transport anisotropy into quantitative agreement with the known Fermi surface geometry within an isotropic relaxation-time approximation. These results resolve a long-standing discrepancy between transport and quantum oscillation measurements in overdoped Tl2201 and establish cryogenic FIB microstructuring as a route to reliable quantitative transport measurements in quantum materials where disorder, inhomogeneity, geometry, or small crystal size have previously limited experimental accuracy.

cond-mat.supr-con↗

arXiv2022

Design of acoustic diffraction plates for manipulating ultrasound in liquid Helium

Many experiments in liquid Helium, such as the optical imaging of exploding electron bubbles, which enables research on individual particles under applied conditions, involve the usage of ultrasound generated by piezoelectric transducers. Previous studies either use planar transducers, which limits the maximum sound intensity and the spatial resolution, or curved transducers, which only allow observations at fixed foci and make it difficult to apply uniform electric fields. In this paper, we introduce the usage of acoustic diffraction plates in liquid Helium to amplify ultrasonic pressure oscillations at an arbitrary set of primary foci coupled with large counts of secondary foci, all of which can be freely moved around by changing the ultrasound frequency. The frequency dependence also allows us to generate controlled Faraday instabilities at the surface, which enables the generation of multi-electron bubbles with desired parameters.

cond-mat.soft↗

arXiv2021

Collision-induced coherent dynamics

In this paper we demonstrate a route to develop coherence in a system of non-driven oscillators. Here, the coherence is brought about via physical collisions through which the oscillators exchange energy. While coherence in the classical situations occurs due to sustained coupling terms in the dynamical equations, collision-induced coherence is enabled solely through strong interactions that are of intermittent nature! We demonstrate this in a Newton's cradle arrangement of oscillators by electrical and optical studies under ambient and vacuum conditions.

nlin.CD↗

arXiv2021

Growth and characterization of high-quality single-crystalline SnTe retaining cubic symmetry down to the lowest temperature studied

SnTe, an archetypical topological crystalline insulator, often shows a transition from a highly symmetric cubic phase to a rhombohedral structure at low temperatures. In order to achieve the highly symmetric cubic phase at low temperatures suitable for quantum behaviour, we have employed the modified Bridgman method to grow a high-quality single-crystalline sample of SnTe. Analysis of the crystal structure using Laue diffraction and rocking curve measurements show a very high degree of single crystallinity of the sample. Resistivity and the specific heat data do not show the signature of structural transition down to the lowest temperature studied. The magnetic susceptibility shows diamagnetic behaviour. All these properties manifest the behaviour of a typical bulk semiconductor with conducting surface states as expected in a topological material. Detailed powder x-ray diffraction measurements show cubic structure in the whole temperature range studied.

cond-mat.mtrl-sci↗

arXiv2021

Anomalies in the temperature evolution of the Dirac states in a topological crystalline insulator SnTe

Discovery of topologically protected surface states, believed to be immune to weak disorder and thermal effects, opened up a new avenue to reveal exotic fundamental science and advanced technology. While time-reversal symmetry plays the key role in most such materials, the bulk crystalline symmetries such as mirror symmetry preserve the topological properties of topological crystalline insulators (TCIs). It is apparent that any structural change may alter the topological properties of TCIs. To investigate this relatively unexplored landscape, we study the temperature evolution of the Dirac fermion states in an archetypical mirror-symmetry protected TCI, SnTe employing high-resolution angle-resolved photoemission spectroscopy and density functional theory studies. Experimental results reveal a perplexing scenario; the bulk bands observed at 22 K move nearer to the Fermi level at 60 K and again shift back to higher binding energies at 120 K. The slope of the surface Dirac bands at 22 K becomes smaller at 60 K and changes back to a larger value at 120 K. Our results from the first-principles calculations suggest that these anomalies can be attributed to the evolution of the hybridization physics with complex structural changes induced by temperature. In addition, we discover drastically reduced intensity of the Dirac states at the Fermi level at high temperatures may be due to complex evolution of anharmonicity, strain, etc. These results address robustness of the topologically protected surface states due to thermal effects and emphasize importance of covalency and anharmonicity in the topological properties of such emerging quantum materials.

cond-mat.mtrl-sci↗