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Pramod K. Sharma

Publications and source records attributed to Pramod K. Sharma.

9 recordsLinked to original sources
arXiv2026

Universal route towards field-free electrically polarity-reversible Josephson diode

The realisation of superconducting diodes that operate without external magnetic fields and allow electrical control of polarity is a key goal for the integration of nonreciprocal elements into cryogenic and quantum technologies. Here, we demonstrate a universal and scalable approach to achieving such field-free and electrically reconfigurable Josephson diode functionality. Our method relies on long Josephson junctions with ferromagnetic barriers and asymmetric current injection - a configuration that inherently breaks both time-reversal and inversion symmetries. We show that the diode polarity is set by an applied bias current and can be reversed using short current pulses, without the need for magnetic fields or thermal cycling. The effect is robust, material-agnostic, and compatible with standard established fabrication processes. Our results provide a practical platform for integrating low-dissipation, programmable diodes into superconducting and quantum electronic circuits

cond-mat.supr-con↗
arXiv2023

Large tuneable exchange fields due to purely paramagnetically limited domain wall superconductivity

The ability to locally apply and tune large magnetic fields is a crucial requirement for several devices, most notably for detection and generation of majorana fermions. Such a functionality can be achieved in Superconductor (S) /Ferromagnet (F) bilayers, where superconductivity is strengthened on top of domain walls due to local lowering of the proximity induced effective exchange fields. This is predicted to result in significant superconducting Tc enhancements and possible complete magnetic controlled switching on and off of the superconducting state. By using thin films of superconducting Nb and ferromagnetic insulating (GdN) bilayers, and through detailed magneto-transport measurements, we demonstrate the previously unobserved phenomena of complete switching in and out of the S state in S/F bilayers. In the thinnest of Nb layers, we estimate that the domain wall state induced tunability of proximity induced exchange fields can be as high as 1.3T with application of in plane external fields of only a few mT.

cond-mat.supr-con↗
arXiv2021

Structural results on lifting, orthogonality and finiteness of idempotents

In this paper, using the canonical correspondence between the idempotents and clopens, we obtain several new results on lifting idempotents. The Zariski clopens of the maximal spectrum are precisely determined, then as an application, lifting idempotents modulo the Jacobson radical is characterized. Lifting idempotents modulo an arbitrary ideal is also characterized in terms of certain connected sets related to that ideal. Then as an application, we obtain that the sum of a lifting ideal and a regular ideal is a lifting ideal. We prove that lifting idempotents preserves the orthogonality in countable cases. The lifting property of an arbitrary morphism of rings is characterized. As another major result, it is proved that the number of idempotents of a ring $R$ is finite if and only if it is of the form $2^κ$ where $κ$ is the cardinal of the connected components of Spec$(R)$. Finally, it is proved that the primitive idempotents of a zero dimensional ring are in 1-1 correspondence with the isolated points of its prime spectrum. These results either generalize or improve several important results in the literature.

math.AC↗
arXiv2021

Comments On " Orbits of automorphism groups of fields"

Let $R$ be a commutative $k-$algebra over a field $k$. Assume $R$ is a noetherian, infinite, integral domain. The group of $k-$automorphisms of $R$,i.e.$Aut_k(R)$ acts in a natural way on $(R-k)$.In the first part of this article, we study the structure of $R$ when the orbit space $(R-k)/Aut_k(R)$ is finite.We note that most of the results, not particularly relevent to fields, in [1,§2] hold in this case as well. Moreover, we prove that $R$ is a field. In the second part, we study a special case of the Conjecture 2.1 in [1] : If $K/k$ is a non trivial field extension where $k$ is algebraically closed and $\mid (K-k)/Aut_k(K) \mid = 1$ then $K$ is algebraically closed. In the end, we give an elementary proof of [1,Theorem 1.1] in case $K$ is finitely generated over its prime subfield.

math.AC↗
arXiv2019

Ideal containment vs. powers

Let $R$ be a commutative ring with identity. In this note, we study the property: If $ I \subsetneqq J$ are ideals in $R$, then $ I^n \subsetneqq J^n$ for all $ n\geq 1$. We define the notion of a big ideal (Definition 1.2). It is noted that the property has close relationship with the notions of reduction of an ideal and Ratliff-Rush ideal [7]. Apart from other results, it is proved that a Noetherian domain satifies the property if and only if every ideal in $R$ is a Ratliff-Rush ideal. We also prove that ideals having no proper reduction are big ideals, and maximal ideals in regular rings are big.

math.AC↗
arXiv2010

A Graphical Representation of Rings via Automorphism Groups

Let $R$ be a commutative ring with identity. We define a graph $Γ_{\aut}(R)$ on $ R$, with vertices elements of $R$, such that any two distinct vertices $x, y$ are adjacent if and only if there exists $σ\in \aut$ such that $σ(x)=y$. The idea is to apply graph theory to study orbit spaces of rings under automorphisms. In this article, we define the notion of a ring of type $n$ for $n\geq 0$ and characterize all rings of type zero. We also characterize local rings $(R,M) $ in which either the subset of units ($\neq 1 $) is connected or the subset $M- \{0\}$ is connected in $Γ_{\aut}(R)$.

math.AC↗
arXiv2007

On Power Stable Ideals

We define the notion of a power stable ideal in a polynomial ring $ R[X]$ over an integral domain $ R $. It is proved that a maximal ideal $χ$ $ M $ in $ R[X]$ is power stable if and only if $ P^t $ is $ P$- primary for all $ t\geq 1 $ for the prime ideal $ P = M \cap R $. Using this we prove that for a Hilbert domain $R$ any radical ideal in $R[X]$ which is a finite intersection G-ideals is power stable. Further, we prove that if $ R $ is a Noetherian integral domain of dimension 1 then any radical ideal in $ R[X] $ is power stable. Finally, it is proved that if every ideal in $ R[X]$ is power stable then $ R $ is a field.

math.AC↗
arXiv2007

Some result on K-algebras

We give a new proof of the classical result due to Rodney Y. Sharp and Peter Vamos on the dimension of tensor product of a finite number of field extensions of a given field.

math.AC↗