Can JSON contained in a string property of another JSON be described via JSON schema?

If I have an object like this:

{
  "name": "John",
  "details": "{"age": 30, "email": "[email protected]"}"
}

Is it possible to describe nested JSON in "details" with a schema inside of an outer schema?

I imagine something like this:

{
  "type": "object",
  "properties": {
    "name": {
      "type": "string"
    },
    "details": {
      "type": "string",
      "contentMediaType": "application/json", 
      "schema": {
        "type": "object",
        "properties": {
           "age": {
             "type": "number"
           },
           "email": {
             "type": "string"
           }
        }
      }
    }
  }
}