HttpPost method in is not adding data (to JSON file) received from ASP.NET MVC application by using Web API for POST operation

JSON File:

{
    "Students": [
{
  "id": 1,
  "name": "Ravi",
  "department": "IT"
},

{
  "id": 2,
  "name": "Raj",
  "department": "hr"
},
{
  "id": 3,
  "name": "avi",
  "department": "it"
}
]}

ASP.NET MVC model classes:

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Department { get; set; }
}

public class Root
{
    public List<Student> Students { get; set; }
}

ASP.NET MVC controller for receiving data from a jQuery POST request, and sending that data to the API:

public class StudentController : Controller
{
    HttpClientHandler _clientHandler = new HttpClientHandler();

    [HttpPost]
    public async Task<List<Student>> AddUser(Student _Students)
    {
        OStudents = new List<Student>();

        using (var httpclient = new HttpClient(_clientHandler))
        {
            StringContent content = new StringContent(JsonConvert.SerializeObject(_Students), Encoding.UTF8, "application/json");

            using (var response = await httpclient.PostAsync("https://localhost:7018/api/Students/AddUser", content))
            {
                string res = await response.Content.ReadAsStringAsync();
                OStudents = JsonConvert.DeserializeObject<List<Student>>(res);
            }
        }

        return OStudents;
    }
}

jQuery code: for sending data to AddUser function:

function AddStudent() {
    oStudent = {
    id: $("#st-Id").val(),
    name: $("#st-Name").val(),
    department: $("#st-Department").val()
};

$.post("/Student/AddUser", oStudent);
$.ajax({
    url: "/Student/AddUser",
    type: 'POST',
    data: oStudent,
    contentType: 'application/json',
    dataType: 'json',
    success: function (msg) {
        alert(msg);
    }
});

Web API files:

Classes:

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Department { get; set; }
}
   
public class Students
{
    public List<Student> students { get; set; }
}   

ApiController for adding data received from ASP.NET MVC application to JSON file

    [HttpPost("AddUser")]
    public IActionResult AddUser(Students _Student)
    {
        var filePath = @"C:/Users/tanmay_pawar/source/repos/CRUDAPI/CRUDAPI/output.json";
        var json = System.IO.File.ReadAllText(filePath);

        Students students = JsonConvert.DeserializeObject<Students>(json);

        students.students.AddRange(_Student.students);

        json = JsonConvert.SerializeObject(students);
        System.IO.File.WriteAllText(filePath, json);

        return Ok();
    }

My POST method in the Web API is receiving null values.