Low dimensional quantum magnets are interesting because of the emerging
collective behavior arising from strong quantum fluctuations. The
one-dimensional (1D) S = 1/2 Heisenberg antiferromagnet is a paradigmatic
example, whose low-energy excitations, known as spinons, carry fractional spin
S = 1/2. These fractional modes can be reconfined by the application of a
staggered magnetic field. Even though considerable progress has been made in
the theoretical understanding of such magnets, experimental realizations of
this low-dimensional physics are relatively rare. This is particularly true for
rare-earth based magnets because of the large effective spin anisotropy induced
by the combination of strong spin-orbit coupling and crystal field splitting.
Here, we demonstrate that the rare-earth perovskite YbAlO3 provides a
realization of a quantum spin S = 1/2 chain material exhibiting both quantum
critical Tomonaga-Luttinger liquid behavior and spinon
confinement-deconfinement transitions in different regions of magnetic
field-temperature phase diagram.Comment: Main text: 25 pages, 7 figures; Supplementary Information: 11 pages,
8 figure
