Publications de Goran Nilsen | EPFL Graph Search

Temperature dependence of the(pi,0)anomaly in the excitation spectrum of the 2D quantum Heisenberg antiferromagnet

Martin Mourigal, Henrik Moodysson Rønnow, Goran Nilsen

It is well established that in the low-temperature limit, the two-dimensional quantum Heisenberg antiferromagnet on a square lattice (2DQHAFSL) exhibits an anomaly in its spectrum at short-wavelengths on the zone-boundary. In the vicinity of the (pi, 0) po ...

IOP PUBLISHING LTD2020

24-spin clusters in the mineral boleite KPb26Ag9Cu24Cl62(OH)(48)

Henrik Moodysson Rønnow, Goran Nilsen, Ivica Zivkovic, Peter Babkevich, Ursula Bengaard Hansen, Nicola Casati

2018

MnO nanoparticles as the cause of ferromagnetism in bulk dilute Mn-doped ZnO

Arnaud Magrez, Henrik Moodysson Rønnow, Goran Nilsen, Diane Virginie Marie Lançon, Ping Huang

We show that the observed ferromagnetic behavior of ZnO lightly doped with Mn coincides with the presence of MnO nanoparticles, whereas cluster-free Mn doped ZnO behaves paramagnetically. This conclusion is reached by a study of the structural and magnetic ...

2016

Fractional excitations in the square-lattice quantum antiferromagnet

Dmitri Ivanov, Bastien Dalla Piazza, Martin Mourigal, Henrik Moodysson Rønnow, Goran Nilsen, Mechthild Enderle

Quantum magnets have occupied the fertile ground between many-body theory and low-temperature experiments on real materials since the early days of quantum mechanics. However, our understanding of even deceptively simple systems of interacting spin-1/2 par ...

Nature Publishing Group2015

One-dimensional quantum magnetism in the anhydrous alum KTi(SO4)(2)

Henrik Moodysson Rønnow, Goran Nilsen

The anhydrous alum KTi(SO4)(2), where the Ti3+ (d(1), S = 1/2) ions form an anisotropic triangular lattice, has been prepared by a new hydrothermal route and characterized by magnetic susceptibility and neutron scattering measurements. Contrary to expectat ...

2015

Electronic structure of KTi(SO4)(2)center dot H2O: An S=1/2 frustrated chain antiferromagnet

Julian Piatek, Henrik Moodysson Rønnow, Goran Nilsen

The compound KTi(SO4)(2)center dot H2O was recently reported as a quasi-one-dimensional spin-1/2 compound with competing antiferromagnetic nearest-neighbor exchange J(1) and next-nearest-neighbor exchange J(2) along the chain with a frustration ratio alpha ...

American Physical Society2013

Low-energy spin dynamics of the s=1/2 kagome system herbertsmithite

Henrik Moodysson Rønnow, Goran Nilsen

The low-energy (epsilon = (h) over bar < 1 meV), low-temperature (T = 0.05 K) spin dynamics of the s = 1/2 kagome candidate herbertsmithite are probed in the presence of magnetic fields up to 2.5 T. The zero-field spectra reveal a very weak continuum of sc ...

Institute of Physics2013

Pair correlations, short-range order, and dispersive excitations in the quasi-kagome quantum magnet volborthite

Henrik Moodysson Rønnow, Goran Nilsen

We present spatial and dynamic information on the s = 1/2 distorted kagome antiferromagnet volborthite, Cu3V2O7(OD)(2) center dot 2D(2)O, obtained by polarized and inelastic neutron scattering. The instantaneous structure factor, S(Q), is dominated by near ...

2011

Spangolite: an s = 1/2 maple leaf lattice antiferromagnet?

Julian Piatek, Henrik Moodysson Rønnow, Goran Nilsen

Spangolite, Cu6Al(SO4)(OH)12Cl·3H2O, is a hydrated layered copper sulfate mineral. The Cu2+ ions of each layer form a systematically depleted triangular lattice which approximates a maple leaf lattice. We present details of the crystal structure, which sug ...

2011

Determination of the single-ion anisotropy energy in a S=5/2 kagome antiferromagnet using x-ray absorption spectroscopy

Henrik Moodysson Rønnow, Goran Nilsen

We report x-ray absorption and x-ray linear dichroism measurements at the Fe L-2,L-3 edges of the geometrically frustrated systems of potassium and hydronium iron jarosite. Comparison with simulated spectra, involving ligand-field multiplet calculations mo ...

2009

Scale-Free Antiferromagnetic Fluctuations in the s=1/2 Kagome Antiferromagnet Herbertsmithite

Julian Piatek, Henrik Moodysson Rønnow, Goran Nilsen

Neutron spectroscopy and diffuse neutron scattering on herbertsmithite [ZnCu3(OH)(6)Cl-2], a near-ideal realization of the s=1/2 kagome antiferromagnet, reveal the hallmark property of a quantum spin liquid: instantaneous short-ranged antiferromagnetic cor ...

2009

A new realisation of the S=1/2 frustrated chain antiferromagnet

Henrik Moodysson Rønnow, Goran Nilsen

American Chemical Society2008