  Chemical pressure is an effective method to tune physical properties,
particularly for diluted magnetic semiconductors (DMS) of which ferromagnetic
ordering is mediated by charge carriers. Via substitution of smaller Ca for
larger Sr, we introduce chemical pressure on (Sr,Na)(Cd,Mn)2As2 to fabricate a
new DMS material (Ca,Na)(Cd,Mn)2As2. Carriers and spins are introduced by
substitutions of (Ca,Na) and (Cd,Mn) respectively. The unit cell volume reduces
by 6.2% after complete substitution of Ca for Sr, suggesting a subsistent
chemical pressure. Importantly the local geometry of [Cd/MnAs4] tetrahedron is
optimized via chemical compression that increases the Mn-As hybridization
leading to enhanced ferromagnetic interactions. As a result, the maximum Curie
temperature (TC) is increased by about 50% while the the maximum saturation
moment increases by over 100% from (Sr,Na)(Cd,Mn)2As2 to (Ca,Na)(Cd,Mn)2As2.
The chemical pressure estimated from the equation of state is equal to an
external physical pressure of 3.6 GPa.
