Papers by Siddharth S Saxena
arXiv (Cornell University), Sep 12, 2022
FePS 3 is a prototype van der Waals layered antiferromagnet and a Mott insulator under ambient co... more FePS 3 is a prototype van der Waals layered antiferromagnet and a Mott insulator under ambient conditions, which has been recently reported to go through a pressure-induced dimensionality crossover and an insulator-to-metal transition. These transitions also lead to the appearance of a novel magnetic metallic state. To further understand these emergent structural and physical properties, we have performed a first-principles study using van der Waals and Hubbard U corrected density functional theory including a random structure search. Our computational study attempts to interpret the experimental coexistence of the low-and intermediate-pressure phases and we predict a novel high-pressure phase with distinctive dimensionality and different possible origins of metallicity.
Tuning dimensionality, magnetism and conduction in van-der-Waals Mott insulators
Bulletin of the American Physical Society, Mar 17, 2021
Physical Review Letters, 2002
We have measured the temperature and field dependence of the resistivity of the unconventional su... more We have measured the temperature and field dependence of the resistivity of the unconventional superconductor Sr 2 RuO 4 at pressures up to 3.3 GPa. Using the Shubnikov-de Haas effect, we find that the Fermi surface sheet believed to be primarily responsible for superconductivity becomes more twodimensional with increasing pressure, a surprising result that is, however, consistent with a recent model of orbital-dependent superconductivity in this system. Many-body enhancements and the superconducting transition temperature all fall gradually with increasing pressure, contrary to previous suggestions of a ferromagnetic quantum critical point at 3 GPa.
Shanghai Cooperation Organization and Prospect of Development in the Eurasia Region
Shanghai Cooperation Organisation and Prospects of Development in the Eurasia Region'. Turki... more Shanghai Cooperation Organisation and Prospects of Development in the Eurasia Region'. Turkish Policy Quarterly. by Siddharth (montu) Saxena. Login or signup to follow this paper. Followers (3). ...
The Asiatic Roots and Rootedness of the Eurasian Project
The Eurasian Project and Europe, 2015
doi: 10.1057/9781137472960 This paper analyses Eurasianism from the standpoint of Asia and specif... more doi: 10.1057/9781137472960 This paper analyses Eurasianism from the standpoint of Asia and specifically Kazakhstan. The Mongol Empire first consolidated Central Asia, the Steppe and Russia with the rest of Europe in the thirteenth century. Eurasia was connected via the Silk Road for centuries, a kind of proto-Eurasian Union, which had its basis in trade. The region has remained inter-connected ever since, negotiating and re-negotiating as rulers have changed. Even as part of the Soviet Union, borders in this region remained permeable. President Nazarbayev’s speech in 1994 layed out his vision of Eurasianism, with its centre in Astana and differs significantly from that of President Putin. The authors consider the drivers of the Eurasian Union as economic, particularly the industrial development and modernisation of the post-Soviet space. It is shown that the Customs Union formed in 2010 has been beneficial and can be considered as a forerunner for the Eurasian Union.
Journal of Eurasian Studies
The article aims to introduce the underlying motivation and conceptual underpinning to the specia... more The article aims to introduce the underlying motivation and conceptual underpinning to the special issue entitled “Globalizing Local Understanding of Fragility in Eurasia.” The main purpose of this article is to problematize the popular opinion and portrayal of Central Asia (Kazakhstan, Kyrgyz Republic, Tajikistan, Turkmenistan, and Uzbekistan) and more generally the countries of Eurasia and the Caucasus as inherently fragile states which are politically unstable and thus on the brink of collapse. This article also seeks to question narratives of modernity that are singular and constantly out of reach for large swathes of the world’s populations because of the narrowness and hegemonic nature of the architecture of global governance. By carefully considering the ways and means through which international institutions categorize countries as fragile and/or failed, the article aims to provide the theoretical foreground for the special issue which focuses on locating inherent community ...
Acta Crystallographica Section A Foundations and Advances, 2021
We report discovery of new metallic and magnetic phases in the van-der-Waals antiferromagnets MPS... more We report discovery of new metallic and magnetic phases in the van-der-Waals antiferromagnets MPS3, where M = Transition Metal, form an ideal playground for tuning both low-dimensional magnetic and electronic properties[1-4]. These are layered honeycomb antiferromagnetic Mott insulators, long studied as near-ideal 2D magnetic systems with a rich variety of magnetic and electric properties across the family.
Technology challenges and opportunities for Kazakhstan’s petroleum industry
Proceedings of the XII Biennial Conference of the European Society for Central Asian Studies: Central Asia: A Maturing Field
Raman-scattering measurement of non-adiabatic phonons in heavily electron-doped graphitic compounds XC$_6$ (X = Ba, Sr, Yb, and Ca)
Bulletin of the American Physical Society, 2017
Submitted for the MAR17 Meeting of The American Physical Society Weak electron-phonon pairing in ... more Submitted for the MAR17 Meeting of The American Physical Society Weak electron-phonon pairing in BiS2 superconductor from first principles RYOSUKE AKASHI, The University of Tokyo, Japan, CORENTIN MORICE1, The University of Cambridge, United Kingdom, TAKASHI KORETSUNE, RIKEN Center for Emergent Matter Science, Japan, SIDDHARTH SAXENA, The University of Cambridge, United Kingdom, RYOTARO ARITA, RIKEN Center for Emergent Matter Science, Japan — The discovery of superconductivity in Bi4O4S3, quickly followed by the one in La(O,F)BiS2, opened up a new research field: novel BiS2 superconductors. Many thorough experimental studies have been conducted but consensus on the nature of superconductivity in these materials has not been reached yet. One of the strongest pieces of evidence until now was the calculation of strong electron-phonon coupling in La(O,F)BiS2 using ab-initio techniques, indicating that superconductivity in these materials is conventional and strongly coupled. Using densit...
16pDA-9 Fermi surfaces and orbital polarization of CeO_<0.5>F_<0.5>BiS_2 revealed by angle-resolved photoemission spectroscopy
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2015
Research data supporting Quantum Critical Phenomena in a Compressible Displacive Ferroelectric
Dielectric constant and loss data as a function of temperature at the pressures given in the fold... more Dielectric constant and loss data as a function of temperature at the pressures given in the folder names along with the resistivity of tin that is used as manometer. Additionally, a workbook showing the numerical calculation methods and then the figures showing the results of these calculations.
Journal of Physics: Condensed Matter, 2019
Novel Superconducting Materials, 2015
Bi4O4S3 was the first superconductor discovered in the BiS2 family of novel superconductors. The ... more Bi4O4S3 was the first superconductor discovered in the BiS2 family of novel superconductors. The subfamily of Bi-O-S systems now expanded andwas probed both theoretically and experimentally. Here we review the experimentalwork done on the Bi-O-S compounds, and compare it with theoretical results obtained using ab-initio methods. In particular we calculate the charge carrier density using an ab-initio calculated density of states, and find a really close agreement with experimental data.
Arxiv preprint cond-mat/ …, 1998
Ambient pressure studies on high purity single crystals of the stoichiometric 4f-electron metal C... more Ambient pressure studies on high purity single crystals of the stoichiometric 4f-electron metal CeNi2Ge2 reveal anomalous low temperature forms of the resistivity which challenge our understanding of the metallic state. Comparisons are made with the isostructural and isoelectronic compound CePd2Si2 near the border of magnetism at high pressure, and possible reasons for this novel non-Fermi liquid form of the resistivity are discussed. Phase diagrams of further anomalies are presented, which involve a loss of resistance at low temperature in some samples of CeNi2Ge2 and unexpected high pressure phases.
Journal of Physics: Condensed Matter, 2000
High purity samples of the paramagnetic 4f-electron metal CeNi 2 Ge 2 exhibit a non-Fermi-liquid ... more High purity samples of the paramagnetic 4f-electron metal CeNi 2 Ge 2 exhibit a non-Fermi-liquid form of the resistivity ρ ∼ T x with x < 1.5 and decreasing towards 1 with increasing sample purity. Measurements of ρ versus T as a function of magnetic field and pressure show that this strange metallic phase is connected to the proximity of an antiferromagnetic quantum critical point as in the isoelectronic relative CePd 2 Si 2 near 2.8 GPa. The anomalous power-law dependence is surprisingly stable over extended ranges in temperature and pressure and challenges current theory of magnetic quantum phase transitions.
Nature Communications, 2020
The occurrence of superconductivity in doped SrTiO3 at low carrier densities points to the presen... more The occurrence of superconductivity in doped SrTiO3 at low carrier densities points to the presence of an unusually strong pairing interaction that has eluded understanding for several decades. We report experimental results showing the pressure dependence of the superconducting transition temperature, Tc, near to optimal doping that sheds light on the nature of this interaction. We find that Tc increases dramatically when the energy gap of the ferroelectric critical modes is suppressed, i.e., as the ferroelectric quantum critical point is approached in a way reminiscent to behaviour observed in magnetic counterparts. However, in contrast to the latter, the coupling of the carriers to the critical modes in ferroelectrics is predicted to be small. We present a quantitative model involving the dynamical screening of the Coulomb interaction and show that an enhancement of Tc near to a ferroelectric quantum critical point can arise due to the virtual exchange of longitudinal hybrid-pola...
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Papers by Siddharth S Saxena