Future information technologies: 3D Quantum Spin Liquid revealed
Two of the four magnetic interactions form a new three-dimensional network of corner-sharing triangles, known as the hyper-hyperkagome lattice, leading to the quantum spin liquid behavior in PbCuTe2O6. © HZB
Quantum Spin Liquids are candidates for potential use in future information technologies. So far, Quantum Spin Liquids have usually only been found in one or two dimensional magnetic systems only. Now an international team led by HZB scientists has investigated crystals of PbCuTe2O6 with neutron experiments at ISIS, NIST and ILL. They found spin liquid behaviour in 3D, due to a so called hyper hyperkagome lattice. The experimental data fit extremely well to theoretical simulations also done at HZB.
IT devices today are based on electronic processes in semiconductors. The next real breakthrough could be to exploit other quantum phenomena, for example interactions between tiny magnetic moments in the material, the so-called spins. So-called quantum-spin liquid materials could be candidates for such new technologies. They differ significantly from conventional magnetic materials because quantum fluctuations dominate the magnetic interactions: Due to geometric constraints in the crystal lattice, spins cannot all "freeze" together in a ground state - they are forced to fluctuate, even at temperatures close to absolute zero.
Quantum spin liquids: a rare phenomenon
Quantum spin liquids are rare and have so far been found mainly in two-dimensional magnetic systems. Three-dimensional isotropic spin liquids are mostly sought in materials where the magnetic ions form pyrochlore or hyperkagome lattices. An international team led by HZB physicist Prof. Bella Lake has now investigated samples of PbCuTe2O6, which has a three-dimensional lattice called hyper-hyperkagome lattice.
Magnetic interactions simulated
HZB physicist Prof. Johannes Reuther calculated the behaviour of such a three-dimensional hyper-hyperkagome lattice with four magnetic interactions and showed that the system exhibits quantum-spin liquid behaviour with a specific magnetic energy spectrum.
Experiments at neutron sources find 3D quantum spin liquid
With neutron experiments at ISIS, UK, ILL, France and NIST, USA the team was able to prove the very subtle signals of this predicted behaviour. "We were surprised how well our data fit into the calculations. This gives us hope that we can really understand what happens in these systems," explains first author Dr. Shravani Chillal, HZB.
- Perovskite solar cells: New Young Investigator Group funded by BMBF at HZBIn the COMET-PV project, Dr Artem Musiienko aims to significantly accelerate the development of perovskite solar cells. He is using robotics and AI to analyse the many variations in the material composition of tin-based perovskites. The physicist will set up a Young Investigator Group at HZB. He will also have an affiliation with Humboldt University in Berlin, where he will gain teaching experience in preparation for a future professorship.
- Mesoporous silicon: Semiconductor with new talentsSilicon is the best-known semiconductor material. However, controlled nanostructuring drastically alters the material's properties. Using a specially developed etching apparatus, a team at HZB has now produced mesoporous silicon layers with countless tiny pores and investigated their electrical and thermal conductivity. For the first time, the researchers elucidated the electronic transport mechanism in this mesoporous silicon. The material has great potential for applications and could also be used to thermally insulate qubits for quantum computers.
- Innovative battery electrode made from tin foamMetal-based electrodes in lithium-ion batteries promise significantly higher capacities than conventional graphite electrodes. Unfortunately, they degrade due to mechanical stress during charging and discharging cycles. A team at HZB has now shown that a highly porous tin foam is much better at absorbing mechanical stress during charging cycles. This makes tin foam an interesting material for lithium batteries.