Magnetic memory device

A magnetic memory device comprising:

• a first electrode;
• a second electrode;
• and
• a magnetoresistance effect element provided between the first electrode and the second electrode,
• wherein
• the magnetoresistance effect element comprises:
• a first magnetic layer;
• a second magnetic layer;
• an insulating layer provided between the first magnetic layer and the second magnetic layer;
• and
• a lanthanoid oxide layer provided between the first electrode and the first magnetic layer, and
• the lanthanoid oxide layer contains at least one lanthanoid element selected from lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), oxygen (O), and at least one predetermined element selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), rhenium (Re), osmium (Os), and platinum (Pt),
• the lanthanoid oxide layer includes a first portion and a second portion, each containing the at least one lanthanoid element and oxygen (O), and a concentration of the at least one predetermined element is higher in the first portion than in the second portion, and the second portion is located between the first portion and the first magnetic layer.