Strategies for increasing the Néel temperature of magnetoelectric Fe2TeO6

Ways to increase the Néel temperature TN in the magnetoelectric Fe2TeO6 antiferromagnet are explored with the help of first-principles calculations. Substitution of larger ions like Zr or Hf for tellurium increases the superexchange angles. The compensating O vacancies tend to form bound complexes with Zr dopants, which do not degrade the electronic band gap. TN is estimated to increase by 15% at 12.5% Te → Zr substitution with such compensation. Substitution of N for O is favorable due to the decreased charge-transfer gap. The overall effect for N(3-) substitution compensated by O vacancies is estimated at 3-4% TN enhancement per 1% O → N substitution. A 1% compressive (0 0 1) epitaxial strain enhances TN by about 6%.