  We report the thermal expansion, critical behavior, magnetocaloric effect
(MCE), and magnetoresistance ($MR$) on the polycrystalline
Mn$_{1.4}$Fe$_{3.6}$Si$_{3}$ compound around the ferromagnetic transition. A
large negative volume thermal expansion ($\alpha_{\rm V}\sim -20 \times
10^{-6}$ K$^{-1}$) is observed across the transition temperature with a strong
anisotropic variation of lattice parameters in the $ab$-plane. The anisotropic
magnetoelasticity arises from the competition between magnetic ordering and
structural deformation which could be responsible for the large MCE ($\Delta
S_{\rm m} \simeq -6$ J/Kg-K) across the magnetic transition in this compound.
The large and negative $MR$ ($\sim -3\%$ in 80 kOe) is also observed at the
transition temperature which can be attributed to the suppression of spin
disorder. Further, the Rhodes-Wolfarth ratio (RWR $> 1$) and identical field
dependence of $MR$ and MCE isotherms indicate the itinerant character of the
$3d$ electrons. The critical exponents determined from the analysis of
magnetization and MCE are consistent with the quasi-two-dimensional (2D) Ising
model with long range exchange interactions which decays as $J(r)\sim
r^{-3.41}$. This unconventional quasi-2D Ising character with long-range
interactions can be ascribed to strong $ab$-plane anisotropy and the
delocalized $3d$ electrons in the studied compound.
