  We investigate the structural and magnetic properties of the new quantum
magnet BaCuTe$_2$O$_6$. This compound is synthesized for the first time in
powder and single crystal form. Synchrotron X-ray and neutron diffraction
reveal a cubic crystal structure (P4$_1$32) where the magnetic Cu$^{2+}$ ions
form a complex network. Physical properties measurements suggest the presence
of antiferromagnetic interactions with a Curie-Weiss temperature of -33K, while
long-range magnetic order occurs at the much lower temperature of ~6.3K. The
magnetic structure, solved using neutron diffraction, reveals antiferromagnetic
order along chains parallel to the a, b and c crystal axes. This is consistent
with the magnetic excitations which resemble the multispinon continuum typical
of the spin-1/2 Heisenberg antiferromagnetic chain. A consistent intrachain
interaction value of ~34K is achieved from the various techniques. Finally the
magnetic structure provides evidence that the chains are coupled together in a
non-colinear arrangement by a much weaker antiferromagnetic, frustrated
hyperkagome interaction.
