  Over the last few years, broken symmetry within crystals has attracted
extensive attention since it can improve the control of light propagation. In
particular, low-symmetry Bravais crystal can support shear polaritons which has
great potential in thermal photonics. In this work, we report a twist-induced
near-field thermal control system based on the low-symmetry Bravais crystal
medium (\b{eta}-Ga2O3). The near-field thermal radiation (NFTR) between such
crystal slabs is nearly four orders of magnitude larger than the blackbody
limit, exceeding the NFTR from other traditional dielectric materials.
Moreover, we show that this crystal can serve as an excellent platform for
twist-induced near-field thermal control. Due to the intrinsic shear effect,
the twist-induced modulation supported by low-symmetry Bravais crystal exceeds
that by high-symmetry crystal. We further clarify how the shear effect affects
the twist-induced thermal-radiation modulation supported by hyperbolic and
elliptical polaritons and show that the shear effect significantly enhances the
twist-induced thermal control induced by the elliptical polariton mode. These
results open new directions for thermal-radiation control in low-symmetry
materials, including geological minerals, common oxides, and organic crystals.
