Mar 20 – 23, 2023
Campus Garching
Europe/Berlin timezone

Bound states and triplet excitations at very high magnetic fields in the Shastry-Sutherland compound, SrCu$_2$(BO$_3$)$_2$

Mar 21, 2023, 11:00 AM
SCC/3-Venus - Venus (Galileo)

SCC/3-Venus - Venus


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Talk (25 + 5 min) Magnetism, Superconductivity, Topological Systems, Magnetic Thin Films an other electronic phenomena Frustrated Magnets 2


Ellen Fogh (École Polytechnique Fédérale de Lausanne)


Chasing new states of quantum matter is a central element in condensed matter physics, motivated both by fundamental curiosity but also by the need for a better understanding of many-body quantum effects for future technologies. Of particular interest are frustrated systems such as the Shastry-Sutherland (SS) model consisting of spin pairs (dimers) embedded in a square lattice. The model has an exact dimer product ground state when the ratio, $J’/J$, between the inter-dimer coupling, $J$, and intra-dimer coupling, $J’$, is less than 0.675 [1]. The network of Cu$^{2+}$ ions in SrCu$_2$(BO$_3$)$_2$ (SCBO) is topologically equivalent to the SS lattice and with $J’/J \sim 0.6$ close to the critical point, this compound presents unique experimental testing grounds for the model. Upon applying a magnetic field, SCBO exhibits a series of phase transitions [3,4] and we study the magnetic excitations upon approaching the first transition at 27T to the 1/8 magnetization plateau using inelastic neutron scattering. At field values much below the transition a novel and unexpected mode shows up. We use state-of-the-art model calculations to identify the nature of this mode: Is it a bound state or a triplet excitation? And why does it appear before the transition?

[1] B. S. Shastry and B. Sutherland, Physica 108B, 1069-1070 (1981)
[2] S. Miyahara and K. Ueda, Phys. Rev. Lett. 82, 3701 (1999)
[3] M. Takigawa et al., Phys. Rev. Lett. 110, 067210 (2013)
[4] P. Corboz and F. Mila, Phys. Rev. Lett. 112, 147203 (2014)

Primary author

Ellen Fogh (École Polytechnique Fédérale de Lausanne)


Dr Bruce Normand (PSI) Ekaterina Pomjakushina (Paul Scherrer Institut) Prof. Frédéric Mila (EPFL) Henrik Rønnow (EPFL) Maciej Bartkowiak (Helmholtz-Zentrum Berlin für Materialien und Energie) Mr Mithilesh Nayak (EPFL) Oleksandr Prokhnenko (HZB)

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