Experimental observation of quantum many-body excitations of E8 symmetry in the Ising chain ferromagnet CoNb2O6Amelin, Kirill; Engelmayer, Johannes; Viirok, Johan; Nagel, Urmas; Rõõm, Toomas; Lorenz, Thomas; Wang, ZhePhysical review B2020 / art. 104431, 5 p. : ill https://doi.org/10.1103/PhysRevB.102.104431

In situ electric-field control of THz nonreciprocal directional dichroism in the multiferroic Ba2CoGe2O7Vít, J.; Viirok, Johan; Peedu, Laur; Rõõm, Toomas; Nagel, Urmas; Kocsis, V.; Tokunaga, Y.; Taguchi, Y.; Tokura, Y.; Kezsmarki, I.; Balla, P.; Penc, K.; Romhanyi, J.; Bordacs, S.Physical review letters2021 / art. 157201, 6 p. : ill https://doi.org/10.1103/PhysRevLett.127.157201

The spectroscopy of the quantum criticality in a transverse field ising chain compound CoNb2O6 [Online resource]Viirok, Johan; Hüvonen, Dan; Rõõm, Toomas; Nagel, UrmasTartu Ülikooli ASTRA projekt PER ASPERA : Funktsionaalsed materjalid ja tehnoloogiad : [4.-5. veebr. 2019, Tartu : teesid]2019 / 1 p http://fmtdk.ut.ee/teesid-2019/

Spin excitations of magnetoelectric LiNiPO4 in multiple magnetic phasesPeedu, Laur; Kocsis, V.; Szaller, D.; Viirok, Johan; Nagel, Urmas; Rõõm, Toomas; Farkas, D.G.; Bordacs, S.; Kamenskyi, D.L.; Zeitler, U.; Tokunaga, Y.; Taguchi, Y.; Tokura, Y.; Kezsmarki, I.Physical review B2019 / art. 024406, 8 p. : ill https://doi.org/10.1103/PhysRevB.100.024406

Terahertz spectroscopy of spin excitations in magnetoelectric LiFePO4 in high magnetic fieldsPeedu, Laur; Kocsis, V.; Szaller, D.; Forrai, B.; Bordacs, S.; Kezsmarki, I.; Viirok, Johan; Nagel, Urmas; Bernath, B.; Kamenskyi, D.L.; Miyata, A.; Portugall, O.; Tokunaga, Y.; Tokura, Y.; Taguchi, Y.; Rõõm, ToomasPhysical review B2022 / art. 134413, 12 p. : ill https://doi.org/10.1103/PhysRevB.106.134413

The study of magnetoelectric effect in multiferroics using THz spectroscopy = Magnetelektrilise nähtuse uurimine multiferroidides THz spektroskoopiagaViirok, Johan2020 https://digikogu.taltech.ee/et/Item/6742e380-e1c5-4f1e-ae2a-8623a8261393