Publications de Noore Elahi Shaik

Confined and Deconfined Spinon Excitations in the Rectangular-lattice Quantum Antiferromagnet

Bruce Normand, Henrik Moodysson Rønnow, Noore Elahi Shaik, Ellen Fogh

Fractionalization remains one of the most fascinating manifestations of strong interactions in quantum many-body systems. In quantum magnetism, the existence of spinons-collective magnetic excitations that behave as quasiparticles with fractional quantum n ...

AMER PHYSICAL SOC2025

Magnon interactions in a moderately correlated Mott insulator

Henrik Moodysson Rønnow, Noore Elahi Shaik, Ellen Fogh

Quantum fluctuations in low-dimensional systems and near quantum phase transitions have significant influences on material properties. Yet, it is difficult to experimentally gauge the strength and importance of quantum fluctuations. Here we provide a reson ...

Nature Research2024

Staggered flux state for rectangular-lattice spin-1/2 Heisenberg antiferromagnets

Dmitri Ivanov, Bastien Dalla Piazza, Henrik Moodysson Rønnow, Noore Elahi Shaik

We investigate the spin-1/2 Heisenberg model on a rectangular lattice, using the Gutzwiller projected variational wave function known as the staggered flux state. Using Monte Carlo techniques, the variational parameters and instantaneous spin-spin correlat ...

AMER PHYSICAL SOC2020

Exact diagonalization study of the Hubbard-parametrized four-spin ring exchange model on a square lattice

Henrik Moodysson Rønnow, Noore Elahi Shaik, Sofie Janas

We have used exact numerical diagonalization to study the excitation spectrum and the dynamic spin correlations in the s = 1/2 next-next-nearest-neighbor Heisenberg antiferromagnet on the square lattice, with additional four-spin ring exchange from higher- ...

AMER PHYSICAL SOC2019

From quantum spin chains to square lattice Heisenberg anti-ferromagnets

Noore Elahi Shaik

This thesis presents a theoretical study of the Heisenberg model on a two dimensional lattice with asymmetric couplings along x and y directions. By gradually varying the coupling along y-direction we traverse the 1D, quasi 1D and 2D domains of this model. ...

EPFL2019

Strain-engineering Mott-insulating La2CuO4

Henrik Moodysson Rønnow, Johan Juul Chang, Yu-Pei Tseng, Noore Elahi Shaik, Yi Tseng, Thorsten Schmitt

The transition temperature T-c of unconventional superconductivity is often tunable. For a monolayer of FeSe, for example, the sweet spot is uniquely bound to titanium-oxide substrates. By contrast for La2-xSrxCuO4 thin films, such substrates are sub-optim ...

Nature Research2019

Electronic and magnetic excitations in the half-stuffed Cu-O planes of Ba2Cu3O4Cl2 measured by resonant inelastic x-ray scattering

Marco Grioni, Bruce Normand, Henrik Moodysson Rønnow, Peter Babkevich, Sara Fatale, Noore Elahi Shaik, Claudia Giuseppina Fatuzzo, Thorsten Schmitt

We use resonant inelastic x-ray scattering (RIXS) at the Cu L3 edge to measure the charge and spin excitations in the “half-stuffed” Cu-O planes of the cuprate antiferromagnet Ba2Cu3O4Cl2. The RIXS line shape reveals distinct contributions to the dd excita ...

2017

J1-J2 square lattice antiferromagnetism in the orbitally quenched insulator MoOPO4

Helmuth Berger, László Forró, Arnaud Magrez, Oleg Yazyev, Bálint Náfrádi, Henrik Moodysson Rønnow, Ivica Zivkovic, Peter Babkevich, Lin Yang, Noore Elahi Shaik

We report magnetic and thermodynamic properties of a 4d1 (Mo5+) magnetic insulator MoOPO4 single crystal, which realizes a J1−J2 Heisenberg spin-1/2 model on a stacked square lattice. The specific-heat measurements show a magnetic transition at 16 K which ...

Amer Physical Soc2017

Magnetic excitations from the two-dimensional interpenetrating Cu framework in Ba2Cu3O4Cl2

Henrik Moodysson Rønnow, Diane Virginie Marie Lançon, Mechthild Enderle, Peter Babkevich, Noore Elahi Shaik

We report detailed neutron scattering studies on Ba2Cu3O4Cl2. The compound consists of two interpenetrating sublattices of Cu, labeled as Cu-A and Cu-B, each of which forms a square-lattice Heisenberg antiferromagnet. The two sublattices order at different ...

Amer Physical Soc2017

Possibility of an unconventional spin state of Ir4+ in Ba21Ir9O43 single crystal

László Forró, Arnaud Magrez, Oleg Yazyev, Alla Arakcheeva, Bálint Náfrádi, Henrik Moodysson Rønnow, Ivica Zivkovic, Jacim Jacimovic, Sergiy Katrych, Andrea Pisoni, Lin Yang, Noore Elahi Shaik

We report the synthesis of single crystals of a novel layered iridate Ba21Ir9O43 and present the crystallographic, transport, and magnetic properties of this material. The compound has a hexagonal structure with two iridium oxide layers stacked along the c ...

Amer Physical Soc2016

Magnons in tetragonal CuO

Marco Grioni, Frédéric Mila, Bastien Dalla Piazza, Henrik Moodysson Rønnow, Simon Karl Moser, Sara Fatale, Noore Elahi Shaik, Thorsten Schmitt

We investigate by resonant inelastic x-ray scattering the magnetic excitations in thin films of tetragonal CuO. We identify a spin wave excitation, dispersing on two cupratelike antiferromagnetic sublattices. Its energy at the boundary of the Brillouin zon ...

2015

Intrachain antiferromagnetic exchange in a 1D branched-chain built of two different copper(II) centres interlinked by end-on azido and phenoxo bridges: electron density map, electrochemical and magnetic properties

Kurt Schenk, Philip Pattison, Krunoslav Prsa, Henrik Moodysson Rønnow, Arash Alahgholipour Omrani, Noore Elahi Shaik

A 1D, end-on azido- and phenoxo-bridged, coordination polymer, Cu-2(mu-NAPPR)(mu(1,1)-N-3)(2) (1), (NAPPR(2-) = 1,3-bis(naphthylideneimino) propane dianion), was synthesized and characterized. The 1D branched-chain is built of two types of slightly di ...

2015