Atlas Search having compound query and sort

I am getting Atlas search error “Failed to run this query. Reason: “compound” unrecognized field “sort””. I have compound query with must operator and after that I am sorting.

[{
“$search”: {
“compound”: {
“must”: [{
“text”: {
“query”: “John”,
“path”: “emp.contract.empFirstName”
}
}, {
“text”: {
“query”: “2023”,
“path”: “emp.contract.strYear”
}
}, {
“text”: {
“query”: “DFW”,
“path”: “location”
}
}

            ],
            "sort": {
              "emp.contract.empLastName": -1
            }
                
        },
        "index": "default"
    }
}

]