Complex sentence: This scenario emerged in the 1990s when particular metallic heterostructures at the atomic limit with a broken spatial symmetry have been found to favor superconductivity.while before a broken spatial symmetry was expected to compete and suppress always the superconducting order.
Split into simpler sentences: This scenario emerged in the 1990s when particular metallic heterostructures at the atomic limit with a broken spatial symmetry have been found to favor superconductivity. Before a broken spatial symmetry was expected to compete and suppress the superconducting order.