Epitaxial growth of bismuth rare earth iron garnet from a flux of bismuth oxide and alkali metal oxide

In the method of growing a monocrystalline bismuth rare earth iron garnet layer of the formula Bi.sub.p A.sub.3-p D.sub.q Fe.sub.5q O.sub.12 wherein 0 <

• p <
• 3, 0 <
• q <
• 5, A is at least one rare earth selected from those elements having atomic numbers 21, 39 and 57 to 91 inclusive and D is at least one element selected from the group consisting of gallium and aluminum by liquid phase epitaxy from a melt on a crystal face of a monocrystalline substrate, the resulting layer having the crystallographic orientation of said crystal face, said melt comprising the components of said garnet and a flux, the improvement wherein the flux is present in a concentration of 60 to 90 mol % of the melt and comprises a mixture of Bi.sub.2 O.sub.3 and Me.sub.2 O.sub.3 wherein Me is at least one element selected from the group consisting of Li, Na, K, Rb and Cs, Me.sub.2 O is present in an amount of from 1% to 6% by weight of the melt and the molar ratio of Bi.sub.2 O.sub.3 :
• Me.sub.2 O.sub.3 in said flux is 100:x where the value of x is such that the mixture has a viscosity of less than 16 centipoises at the growth temperature and said flux is capable of forming a eutectic composition having a eutectic temperature below the melting point of pure Bi.sub.2 O.sub.3.