Beyond Single Tetrahedron Physics of Breathing Pyrochlore Compound Ba3Yb2Zn5O11
Rabindranath Bag,1, ∗Sachith E. Dissanayake,1, ∗Han Yan,2Zhenzhong Shi,1David
Graf,3Eun Sang Choi,3Casey Marjerrison,1Franz Lang,4Tom Lancaster,5Yiming Qiu,6
Wangchun Chen,6Stephen J. Blundell,4Andriy H. Nevidomskyy,7and Sara Haravifard1, 8, †
1Department of Physics, Duke University, Durham, NC 27708, USA
2Rice Academy of Fellows, Rice University, Houston, TX 77005, USA
3National High Magnetic Field Laboratory and Department of Physics,
Florida State University, Tallahassee, Florida 32310, USA.
4Clarendon Laboratory & Physics Department, University of Oxford,
Parks Road, Oxford OX1 3PU, United Kingdom
5Department of Physics, Centre for Materials Physics,
Durham University, Durham DH1 3LE, United Kingdom
6NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
7Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
8Department of Materials Sciences and Mechanical Engineering, Duke University, Durham, NC 27708, USA
(Dated: October 14, 2022)
Recently a new class of quantum magnets, the so-called breathing pyrochlore spin systems, have
attracted much attention due to their potential to host exotic emergent phenomena. Here, we present
magnetometry, heat capacity, thermal conductivity, Muon-spin relaxation, and polarized inelastic
neutron scattering measurements performed on high-quality single-crystal samples of breathing py-
rochlore compound Ba3Yb2Zn5O11. We interpret these results using a simplified toy model and
provide a new insight into the low-energy physics of this system beyond the single-tetrahedron
physics proposed previously.
Frustrated quantum magnets provide a fruitful arena
to search for novel quantum phenomena [1,2]. Py-
rochlore lattice magnets, in which magnetic ions form
corner-sharing regular tetrahedra, are one of the most
studied frustrated systems in three-dimension [3–6]. In
the pyrochlore system the conventional magnetic order-
ing is suppressed by the geometrically frustrated lat-
tice, consequently resulting in emergence of exotic phases
[7–19]. Recently a new class of systems, the so-called
breathing pyrochlore magnets, have attracted much at-
tention due to their potential to host exotic phenom-
ena and topological phases [20–23]. In breathing py-
rochlore compounds the lattice inversion symmetry at
each site is broken due to the different sizes of up-
pointing and down-pointing tetrahedra, thus resulting
in large Dzyaloshinskii-Moriya (DM) interactions on the
two tetrahedra [24] (see Fig. 1(a,b) for the structure
of breathing pyrochlores). On the theory front, recent
works have shown that breathing pyrochlore spin systems
can host novel physics including classical rank-2 U(1)
spin-liquid states [25], quantum fractons [26], competing
quantum spin liquids [27], and hedgehog lattices of mag-
netic monopoles and antimonopoles [23]. Thus, it is of
great interest to synthesize and understand breathing py-
rochlore materials. The majority of the work performed
on the breathing pyrochlore-based compounds have fo-
cused on Cr-based spinels with S= 3/2 [28–36], while
the studies performed on quantum systems with S= 1/2
remain limited to Ba3Yb2Zn5O11 in powder form [37–42].
Our recent work reported the first comprehensive neutron
scattering studies performed on single-crystal sample of
Ba3Yb2Zn5O11 [43].
We successfully grew single crystal samples of breath-
ing pyrochlore Ba3Yb2Zn5O11 using the modified optical
floating zone technique [43]. Inelastic neutron scatter-
ing studies using our single crystal sample revealed that
the single-tetrahedron model with isolated tetrahedra
can explain the high-temperature and high-energy regime
of the collected data [43]. However, the diffuse neu-
tron scattering performed at low-temperature and low-
energy reveals features which cannot be understood with
this model [43]. Pair distribution function (PDF) anal-
yses performed on high quality powder neutron diffrac-
tion data provided evidence for the absence of chemical
disorder within experimental resolution. Single crystal
X-ray diffraction studies also found no evidence of site
disorder [43]. Diffuse neutron scattering on single crys-
tal samples [43], and the low temperature heat capacity
data collected on powder samples [39,42] suggest that
physics beyond the single tetrahedron, with small but
finite inter-tetrahedron interactions, is essential to cap-
ture the behavior of this quantum breathing pyrochlore
system. This calls for additional experimental probes
at low temperature with higher resolution, so that we
can study the subtle changes in magnetic properties of
Ba3Yb2Zn5O11 with higher accuracy.
In this letter, we report low-temperature heat capac-
ity measurements in applied field, ultra-sensitive mag-
netic susceptibility, thermal conductivity, muon spin re-
laxation (µ+SR), and polarized inelastic neutron scatter-
ing measurements of the ytterbium based breathing py-
rochlore compound Ba3Yb2Zn5O11 in single-crystalline
form, to investigate the intrinsic low temperature mag-
arXiv:2210.06534v1 [cond-mat.str-el] 12 Oct 2022